michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: /*
michael@0:  * Encryption/decryption routines for CMS implementation, none of which are exported.
michael@0:  */
michael@0: 
michael@0: #include "cmslocal.h"
michael@0: 
michael@0: #include "secoid.h"
michael@0: #include "secitem.h"
michael@0: #include "pk11func.h"
michael@0: #include "secerr.h"
michael@0: #include "secpkcs5.h"
michael@0: 
michael@0: /*
michael@0:  * -------------------------------------------------------------------
michael@0:  * Cipher stuff.
michael@0:  */
michael@0: 
michael@0: typedef SECStatus (*nss_cms_cipher_function) (void *, unsigned char *, unsigned int *,
michael@0: 					unsigned int, const unsigned char *, unsigned int);
michael@0: typedef SECStatus (*nss_cms_cipher_destroy) (void *, PRBool);
michael@0: 
michael@0: #define BLOCK_SIZE 4096
michael@0: 
michael@0: struct NSSCMSCipherContextStr {
michael@0:     void *		cx;			/* PK11 cipher context */
michael@0:     nss_cms_cipher_function doit;
michael@0:     nss_cms_cipher_destroy destroy;
michael@0:     PRBool		encrypt;		/* encrypt / decrypt switch */
michael@0:     int			block_size;		/* block & pad sizes for cipher */
michael@0:     int			pad_size;
michael@0:     int			pending_count;		/* pending data (not yet en/decrypted */
michael@0:     unsigned char	pending_buf[BLOCK_SIZE];/* because of blocking */
michael@0: };
michael@0: 
michael@0: /*
michael@0:  * NSS_CMSCipherContext_StartDecrypt - create a cipher context to do decryption
michael@0:  * based on the given bulk encryption key and algorithm identifier (which 
michael@0:  * may include an iv).
michael@0:  *
michael@0:  * XXX Once both are working, it might be nice to combine this and the
michael@0:  * function below (for starting up encryption) into one routine, and just
michael@0:  * have two simple cover functions which call it. 
michael@0:  */
michael@0: NSSCMSCipherContext *
michael@0: NSS_CMSCipherContext_StartDecrypt(PK11SymKey *key, SECAlgorithmID *algid)
michael@0: {
michael@0:     NSSCMSCipherContext *cc;
michael@0:     void *ciphercx;
michael@0:     CK_MECHANISM_TYPE cryptoMechType;
michael@0:     PK11SlotInfo *slot;
michael@0:     SECOidTag algtag;
michael@0:     SECItem *param = NULL;
michael@0: 
michael@0:     algtag = SECOID_GetAlgorithmTag(algid);
michael@0: 
michael@0:     /* set param and mechanism */
michael@0:     if (SEC_PKCS5IsAlgorithmPBEAlg(algid)) {
michael@0: 	SECItem *pwitem;
michael@0: 
michael@0: 	pwitem = PK11_GetSymKeyUserData(key);
michael@0: 	if (!pwitem) 
michael@0: 	    return NULL;
michael@0: 
michael@0: 	cryptoMechType = PK11_GetPBECryptoMechanism(algid, &param, pwitem);
michael@0: 	if (cryptoMechType == CKM_INVALID_MECHANISM) {
michael@0: 	    SECITEM_FreeItem(param,PR_TRUE);
michael@0: 	    return NULL;
michael@0: 	}
michael@0: 
michael@0:     } else {
michael@0: 	cryptoMechType = PK11_AlgtagToMechanism(algtag);
michael@0: 	if ((param = PK11_ParamFromAlgid(algid)) == NULL)
michael@0: 	    return NULL;
michael@0:     }
michael@0: 
michael@0:     cc = (NSSCMSCipherContext *)PORT_ZAlloc(sizeof(NSSCMSCipherContext));
michael@0:     if (cc == NULL) {
michael@0: 	SECITEM_FreeItem(param,PR_TRUE);
michael@0: 	return NULL;
michael@0:     }
michael@0: 
michael@0:     /* figure out pad and block sizes */
michael@0:     cc->pad_size = PK11_GetBlockSize(cryptoMechType, param);
michael@0:     slot = PK11_GetSlotFromKey(key);
michael@0:     cc->block_size = PK11_IsHW(slot) ? BLOCK_SIZE : cc->pad_size;
michael@0:     PK11_FreeSlot(slot);
michael@0: 
michael@0:     /* create PK11 cipher context */
michael@0:     ciphercx = PK11_CreateContextBySymKey(cryptoMechType, CKA_DECRYPT, 
michael@0: 					  key, param);
michael@0:     SECITEM_FreeItem(param, PR_TRUE);
michael@0:     if (ciphercx == NULL) {
michael@0: 	PORT_Free (cc);
michael@0: 	return NULL;
michael@0:     }
michael@0: 
michael@0:     cc->cx = ciphercx;
michael@0:     cc->doit =  (nss_cms_cipher_function) PK11_CipherOp;
michael@0:     cc->destroy = (nss_cms_cipher_destroy) PK11_DestroyContext;
michael@0:     cc->encrypt = PR_FALSE;
michael@0:     cc->pending_count = 0;
michael@0: 
michael@0:     return cc;
michael@0: }
michael@0: 
michael@0: /*
michael@0:  * NSS_CMSCipherContext_StartEncrypt - create a cipher object to do encryption,
michael@0:  * based on the given bulk encryption key and algorithm tag.  Fill in the 
michael@0:  * algorithm identifier (which may include an iv) appropriately.
michael@0:  *
michael@0:  * XXX Once both are working, it might be nice to combine this and the
michael@0:  * function above (for starting up decryption) into one routine, and just
michael@0:  * have two simple cover functions which call it. 
michael@0:  */
michael@0: NSSCMSCipherContext *
michael@0: NSS_CMSCipherContext_StartEncrypt(PLArenaPool *poolp, PK11SymKey *key, SECAlgorithmID *algid)
michael@0: {
michael@0:     NSSCMSCipherContext *cc;
michael@0:     void *ciphercx;
michael@0:     SECStatus rv;
michael@0:     CK_MECHANISM_TYPE cryptoMechType;
michael@0:     PK11SlotInfo *slot;
michael@0:     SECItem *param = NULL;
michael@0:     PRBool needToEncodeAlgid = PR_FALSE;
michael@0:     SECOidTag algtag = SECOID_GetAlgorithmTag(algid);
michael@0: 
michael@0:     /* set param and mechanism */
michael@0:     if (SEC_PKCS5IsAlgorithmPBEAlg(algid)) {
michael@0: 	SECItem *pwitem;
michael@0: 
michael@0: 	pwitem = PK11_GetSymKeyUserData(key);
michael@0: 	if (!pwitem) 
michael@0: 	    return NULL;
michael@0: 
michael@0: 	cryptoMechType = PK11_GetPBECryptoMechanism(algid, &param, pwitem);
michael@0: 	if (cryptoMechType == CKM_INVALID_MECHANISM) {
michael@0: 	    SECITEM_FreeItem(param,PR_TRUE);
michael@0: 	    return NULL;
michael@0: 	}
michael@0:     } else {
michael@0: 	cryptoMechType = PK11_AlgtagToMechanism(algtag);
michael@0: 	if ((param = PK11_GenerateNewParam(cryptoMechType, key)) == NULL)
michael@0: 	    return NULL;
michael@0: 	needToEncodeAlgid = PR_TRUE;
michael@0:     }
michael@0: 
michael@0:     cc = (NSSCMSCipherContext *)PORT_ZAlloc(sizeof(NSSCMSCipherContext));
michael@0:     if (cc == NULL) {
michael@0: 	goto loser;
michael@0:     }
michael@0: 
michael@0:     /* now find pad and block sizes for our mechanism */
michael@0:     cc->pad_size = PK11_GetBlockSize(cryptoMechType, param);
michael@0:     slot = PK11_GetSlotFromKey(key);
michael@0:     cc->block_size = PK11_IsHW(slot) ? BLOCK_SIZE : cc->pad_size;
michael@0:     PK11_FreeSlot(slot);
michael@0: 
michael@0:     /* and here we go, creating a PK11 cipher context */
michael@0:     ciphercx = PK11_CreateContextBySymKey(cryptoMechType, CKA_ENCRYPT, 
michael@0: 					  key, param);
michael@0:     if (ciphercx == NULL) {
michael@0: 	PORT_Free(cc);
michael@0: 	cc = NULL;
michael@0: 	goto loser;
michael@0:     }
michael@0: 
michael@0:     /*
michael@0:      * These are placed after the CreateContextBySymKey() because some
michael@0:      * mechanisms have to generate their IVs from their card (i.e. FORTEZZA).
michael@0:      * Don't move it from here.
michael@0:      * XXX is that right? the purpose of this is to get the correct algid
michael@0:      *     containing the IVs etc. for encoding. this means we need to set this up
michael@0:      *     BEFORE encoding the algid in the contentInfo, right?
michael@0:      */
michael@0:     if (needToEncodeAlgid) {
michael@0: 	rv = PK11_ParamToAlgid(algtag, param, poolp, algid);
michael@0: 	if(rv != SECSuccess) {
michael@0: 	    PORT_Free(cc);
michael@0: 	    cc = NULL;
michael@0: 	    goto loser;
michael@0: 	}
michael@0:     }
michael@0: 
michael@0:     cc->cx = ciphercx;
michael@0:     cc->doit = (nss_cms_cipher_function)PK11_CipherOp;
michael@0:     cc->destroy = (nss_cms_cipher_destroy)PK11_DestroyContext;
michael@0:     cc->encrypt = PR_TRUE;
michael@0:     cc->pending_count = 0;
michael@0: 
michael@0: loser:
michael@0:     SECITEM_FreeItem(param, PR_TRUE);
michael@0: 
michael@0:     return cc;
michael@0: }
michael@0: 
michael@0: void
michael@0: NSS_CMSCipherContext_Destroy(NSSCMSCipherContext *cc)
michael@0: {
michael@0:     PORT_Assert(cc != NULL);
michael@0:     if (cc == NULL)
michael@0: 	return;
michael@0:     (*cc->destroy)(cc->cx, PR_TRUE);
michael@0:     PORT_Free(cc);
michael@0: }
michael@0: 
michael@0: /*
michael@0:  * NSS_CMSCipherContext_DecryptLength - find the output length of the next call to decrypt.
michael@0:  *
michael@0:  * cc - the cipher context
michael@0:  * input_len - number of bytes used as input
michael@0:  * final - true if this is the final chunk of data
michael@0:  *
michael@0:  * Result can be used to perform memory allocations.  Note that the amount
michael@0:  * is exactly accurate only when not doing a block cipher or when final
michael@0:  * is false, otherwise it is an upper bound on the amount because until
michael@0:  * we see the data we do not know how many padding bytes there are
michael@0:  * (always between 1 and bsize).
michael@0:  *
michael@0:  * Note that this can return zero, which does not mean that the decrypt
michael@0:  * operation can be skipped!  (It simply means that there are not enough
michael@0:  * bytes to make up an entire block; the bytes will be reserved until
michael@0:  * there are enough to encrypt/decrypt at least one block.)  However,
michael@0:  * if zero is returned it *does* mean that no output buffer need be
michael@0:  * passed in to the subsequent decrypt operation, as no output bytes
michael@0:  * will be stored.
michael@0:  */
michael@0: unsigned int
michael@0: NSS_CMSCipherContext_DecryptLength(NSSCMSCipherContext *cc, unsigned int input_len, PRBool final)
michael@0: {
michael@0:     int blocks, block_size;
michael@0: 
michael@0:     PORT_Assert (! cc->encrypt);
michael@0: 
michael@0:     block_size = cc->block_size;
michael@0: 
michael@0:     /*
michael@0:      * If this is not a block cipher, then we always have the same
michael@0:      * number of output bytes as we had input bytes.
michael@0:      */
michael@0:     if (block_size == 0)
michael@0: 	return input_len;
michael@0: 
michael@0:     /*
michael@0:      * On the final call, we will always use up all of the pending
michael@0:      * bytes plus all of the input bytes, *but*, there will be padding
michael@0:      * at the end and we cannot predict how many bytes of padding we
michael@0:      * will end up removing.  The amount given here is actually known
michael@0:      * to be at least 1 byte too long (because we know we will have
michael@0:      * at least 1 byte of padding), but seemed clearer/better to me.
michael@0:      */
michael@0:     if (final)
michael@0: 	return cc->pending_count + input_len;
michael@0: 
michael@0:     /*
michael@0:      * Okay, this amount is exactly what we will output on the
michael@0:      * next cipher operation.  We will always hang onto the last
michael@0:      * 1 - block_size bytes for non-final operations.  That is,
michael@0:      * we will do as many complete blocks as we can *except* the
michael@0:      * last block (complete or partial).  (This is because until
michael@0:      * we know we are at the end, we cannot know when to interpret
michael@0:      * and removing the padding byte(s), which are guaranteed to
michael@0:      * be there.)
michael@0:      */
michael@0:     blocks = (cc->pending_count + input_len - 1) / block_size;
michael@0:     return blocks * block_size;
michael@0: }
michael@0: 
michael@0: /*
michael@0:  * NSS_CMSCipherContext_EncryptLength - find the output length of the next call to encrypt.
michael@0:  *
michael@0:  * cc - the cipher context
michael@0:  * input_len - number of bytes used as input
michael@0:  * final - true if this is the final chunk of data
michael@0:  *
michael@0:  * Result can be used to perform memory allocations.
michael@0:  *
michael@0:  * Note that this can return zero, which does not mean that the encrypt
michael@0:  * operation can be skipped!  (It simply means that there are not enough
michael@0:  * bytes to make up an entire block; the bytes will be reserved until
michael@0:  * there are enough to encrypt/decrypt at least one block.)  However,
michael@0:  * if zero is returned it *does* mean that no output buffer need be
michael@0:  * passed in to the subsequent encrypt operation, as no output bytes
michael@0:  * will be stored.
michael@0:  */
michael@0: unsigned int
michael@0: NSS_CMSCipherContext_EncryptLength(NSSCMSCipherContext *cc, unsigned int input_len, PRBool final)
michael@0: {
michael@0:     int blocks, block_size;
michael@0:     int pad_size;
michael@0: 
michael@0:     PORT_Assert (cc->encrypt);
michael@0: 
michael@0:     block_size = cc->block_size;
michael@0:     pad_size = cc->pad_size;
michael@0: 
michael@0:     /*
michael@0:      * If this is not a block cipher, then we always have the same
michael@0:      * number of output bytes as we had input bytes.
michael@0:      */
michael@0:     if (block_size == 0)
michael@0: 	return input_len;
michael@0: 
michael@0:     /*
michael@0:      * On the final call, we only send out what we need for
michael@0:      * remaining bytes plus the padding.  (There is always padding,
michael@0:      * so even if we have an exact number of blocks as input, we
michael@0:      * will add another full block that is just padding.)
michael@0:      */
michael@0:     if (final) {
michael@0: 	if (pad_size == 0) {
michael@0:     	    return cc->pending_count + input_len;
michael@0: 	} else {
michael@0:     	    blocks = (cc->pending_count + input_len) / pad_size;
michael@0: 	    blocks++;
michael@0: 	    return blocks*pad_size;
michael@0: 	}
michael@0:     }
michael@0: 
michael@0:     /*
michael@0:      * Now, count the number of complete blocks of data we have.
michael@0:      */
michael@0:     blocks = (cc->pending_count + input_len) / block_size;
michael@0: 
michael@0: 
michael@0:     return blocks * block_size;
michael@0: }
michael@0: 
michael@0: 
michael@0: /*
michael@0:  * NSS_CMSCipherContext_Decrypt - do the decryption
michael@0:  *
michael@0:  * cc - the cipher context
michael@0:  * output - buffer for decrypted result bytes
michael@0:  * output_len_p - number of bytes in output
michael@0:  * max_output_len - upper bound on bytes to put into output
michael@0:  * input - pointer to input bytes
michael@0:  * input_len - number of input bytes
michael@0:  * final - true if this is the final chunk of data
michael@0:  *
michael@0:  * Decrypts a given length of input buffer (starting at "input" and
michael@0:  * containing "input_len" bytes), placing the decrypted bytes in
michael@0:  * "output" and storing the output length in "*output_len_p".
michael@0:  * "cc" is the return value from NSS_CMSCipher_StartDecrypt.
michael@0:  * When "final" is true, this is the last of the data to be decrypted.
michael@0:  *
michael@0:  * This is much more complicated than it sounds when the cipher is
michael@0:  * a block-type, meaning that the decryption function will only
michael@0:  * operate on whole blocks.  But our caller is operating stream-wise,
michael@0:  * and can pass in any number of bytes.  So we need to keep track
michael@0:  * of block boundaries.  We save excess bytes between calls in "cc".
michael@0:  * We also need to determine which bytes are padding, and remove
michael@0:  * them from the output.  We can only do this step when we know we
michael@0:  * have the final block of data.  PKCS #7 specifies that the padding
michael@0:  * used for a block cipher is a string of bytes, each of whose value is
michael@0:  * the same as the length of the padding, and that all data is padded.
michael@0:  * (Even data that starts out with an exact multiple of blocks gets
michael@0:  * added to it another block, all of which is padding.)
michael@0:  */ 
michael@0: SECStatus
michael@0: NSS_CMSCipherContext_Decrypt(NSSCMSCipherContext *cc, unsigned char *output,
michael@0: 		  unsigned int *output_len_p, unsigned int max_output_len,
michael@0: 		  const unsigned char *input, unsigned int input_len,
michael@0: 		  PRBool final)
michael@0: {
michael@0:     int blocks, bsize, pcount, padsize;
michael@0:     unsigned int max_needed, ifraglen, ofraglen, output_len;
michael@0:     unsigned char *pbuf;
michael@0:     SECStatus rv;
michael@0: 
michael@0:     PORT_Assert (! cc->encrypt);
michael@0: 
michael@0:     /*
michael@0:      * Check that we have enough room for the output.  Our caller should
michael@0:      * already handle this; failure is really an internal error (i.e. bug).
michael@0:      */
michael@0:     max_needed = NSS_CMSCipherContext_DecryptLength(cc, input_len, final);
michael@0:     PORT_Assert (max_output_len >= max_needed);
michael@0:     if (max_output_len < max_needed) {
michael@0: 	/* PORT_SetError (XXX); */
michael@0: 	return SECFailure;
michael@0:     }
michael@0: 
michael@0:     /*
michael@0:      * hardware encryption does not like small decryption sizes here, so we
michael@0:      * allow both blocking and padding.
michael@0:      */
michael@0:     bsize = cc->block_size;
michael@0:     padsize = cc->pad_size;
michael@0: 
michael@0:     /*
michael@0:      * When no blocking or padding work to do, we can simply call the
michael@0:      * cipher function and we are done.
michael@0:      */
michael@0:     if (bsize == 0) {
michael@0: 	return (* cc->doit) (cc->cx, output, output_len_p, max_output_len,
michael@0: 			      input, input_len);
michael@0:     }
michael@0: 
michael@0:     pcount = cc->pending_count;
michael@0:     pbuf = cc->pending_buf;
michael@0: 
michael@0:     output_len = 0;
michael@0: 
michael@0:     if (pcount) {
michael@0: 	/*
michael@0: 	 * Try to fill in an entire block, starting with the bytes
michael@0: 	 * we already have saved away.
michael@0: 	 */
michael@0: 	while (input_len && pcount < bsize) {
michael@0: 	    pbuf[pcount++] = *input++;
michael@0: 	    input_len--;
michael@0: 	}
michael@0: 	/*
michael@0: 	 * If we have at most a whole block and this is not our last call,
michael@0: 	 * then we are done for now.  (We do not try to decrypt a lone
michael@0: 	 * single block because we cannot interpret the padding bytes
michael@0: 	 * until we know we are handling the very last block of all input.)
michael@0: 	 */
michael@0: 	if (input_len == 0 && !final) {
michael@0: 	    cc->pending_count = pcount;
michael@0: 	    if (output_len_p)
michael@0: 		*output_len_p = 0;
michael@0: 	    return SECSuccess;
michael@0: 	}
michael@0: 	/*
michael@0: 	 * Given the logic above, we expect to have a full block by now.
michael@0: 	 * If we do not, there is something wrong, either with our own
michael@0: 	 * logic or with (length of) the data given to us.
michael@0: 	 */
michael@0: 	if ((padsize != 0) && (pcount % padsize) != 0) {
michael@0: 	    PORT_Assert (final);	
michael@0: 	    PORT_SetError (SEC_ERROR_BAD_DATA);
michael@0: 	    return SECFailure;
michael@0: 	}
michael@0: 	/*
michael@0: 	 * Decrypt the block.
michael@0: 	 */
michael@0: 	rv = (*cc->doit)(cc->cx, output, &ofraglen, max_output_len,
michael@0: 			    pbuf, pcount);
michael@0: 	if (rv != SECSuccess)
michael@0: 	    return rv;
michael@0: 
michael@0: 	/*
michael@0: 	 * For now anyway, all of our ciphers have the same number of
michael@0: 	 * bytes of output as they do input.  If this ever becomes untrue,
michael@0: 	 * then NSS_CMSCipherContext_DecryptLength needs to be made smarter!
michael@0: 	 */
michael@0: 	PORT_Assert(ofraglen == pcount);
michael@0: 
michael@0: 	/*
michael@0: 	 * Account for the bytes now in output.
michael@0: 	 */
michael@0: 	max_output_len -= ofraglen;
michael@0: 	output_len += ofraglen;
michael@0: 	output += ofraglen;
michael@0:     }
michael@0: 
michael@0:     /*
michael@0:      * If this is our last call, we expect to have an exact number of
michael@0:      * blocks left to be decrypted; we will decrypt them all.
michael@0:      * 
michael@0:      * If not our last call, we always save between 1 and bsize bytes
michael@0:      * until next time.  (We must do this because we cannot be sure
michael@0:      * that none of the decrypted bytes are padding bytes until we
michael@0:      * have at least another whole block of data.  You cannot tell by
michael@0:      * looking -- the data could be anything -- you can only tell by
michael@0:      * context, knowing you are looking at the last block.)  We could
michael@0:      * decrypt a whole block now but it is easier if we just treat it
michael@0:      * the same way we treat partial block bytes.
michael@0:      */
michael@0:     if (final) {
michael@0: 	if (padsize) {
michael@0: 	    blocks = input_len / padsize;
michael@0: 	    ifraglen = blocks * padsize;
michael@0: 	} else ifraglen = input_len;
michael@0: 	PORT_Assert (ifraglen == input_len);
michael@0: 
michael@0: 	if (ifraglen != input_len) {
michael@0: 	    PORT_SetError(SEC_ERROR_BAD_DATA);
michael@0: 	    return SECFailure;
michael@0: 	}
michael@0:     } else {
michael@0: 	blocks = (input_len - 1) / bsize;
michael@0: 	ifraglen = blocks * bsize;
michael@0: 	PORT_Assert (ifraglen < input_len);
michael@0: 
michael@0: 	pcount = input_len - ifraglen;
michael@0: 	PORT_Memcpy (pbuf, input + ifraglen, pcount);
michael@0: 	cc->pending_count = pcount;
michael@0:     }
michael@0: 
michael@0:     if (ifraglen) {
michael@0: 	rv = (* cc->doit)(cc->cx, output, &ofraglen, max_output_len,
michael@0: 			    input, ifraglen);
michael@0: 	if (rv != SECSuccess)
michael@0: 	    return rv;
michael@0: 
michael@0: 	/*
michael@0: 	 * For now anyway, all of our ciphers have the same number of
michael@0: 	 * bytes of output as they do input.  If this ever becomes untrue,
michael@0: 	 * then sec_PKCS7DecryptLength needs to be made smarter!
michael@0: 	 */
michael@0: 	PORT_Assert (ifraglen == ofraglen);
michael@0: 	if (ifraglen != ofraglen) {
michael@0: 	    PORT_SetError(SEC_ERROR_BAD_DATA);
michael@0: 	    return SECFailure;
michael@0: 	}
michael@0: 
michael@0: 	output_len += ofraglen;
michael@0:     } else {
michael@0: 	ofraglen = 0;
michael@0:     }
michael@0: 
michael@0:     /*
michael@0:      * If we just did our very last block, "remove" the padding by
michael@0:      * adjusting the output length.
michael@0:      */
michael@0:     if (final && (padsize != 0)) {
michael@0: 	unsigned int padlen = *(output + ofraglen - 1);
michael@0: 
michael@0: 	if (padlen == 0 || padlen > padsize) {
michael@0: 	    PORT_SetError(SEC_ERROR_BAD_DATA);
michael@0: 	    return SECFailure;
michael@0: 	}
michael@0: 	output_len -= padlen;
michael@0:     }
michael@0: 
michael@0:     PORT_Assert (output_len_p != NULL || output_len == 0);
michael@0:     if (output_len_p != NULL)
michael@0: 	*output_len_p = output_len;
michael@0: 
michael@0:     return SECSuccess;
michael@0: }
michael@0: 
michael@0: /*
michael@0:  * NSS_CMSCipherContext_Encrypt - do the encryption
michael@0:  *
michael@0:  * cc - the cipher context
michael@0:  * output - buffer for decrypted result bytes
michael@0:  * output_len_p - number of bytes in output
michael@0:  * max_output_len - upper bound on bytes to put into output
michael@0:  * input - pointer to input bytes
michael@0:  * input_len - number of input bytes
michael@0:  * final - true if this is the final chunk of data
michael@0:  *
michael@0:  * Encrypts a given length of input buffer (starting at "input" and
michael@0:  * containing "input_len" bytes), placing the encrypted bytes in
michael@0:  * "output" and storing the output length in "*output_len_p".
michael@0:  * "cc" is the return value from NSS_CMSCipher_StartEncrypt.
michael@0:  * When "final" is true, this is the last of the data to be encrypted.
michael@0:  *
michael@0:  * This is much more complicated than it sounds when the cipher is
michael@0:  * a block-type, meaning that the encryption function will only
michael@0:  * operate on whole blocks.  But our caller is operating stream-wise,
michael@0:  * and can pass in any number of bytes.  So we need to keep track
michael@0:  * of block boundaries.  We save excess bytes between calls in "cc".
michael@0:  * We also need to add padding bytes at the end.  PKCS #7 specifies
michael@0:  * that the padding used for a block cipher is a string of bytes,
michael@0:  * each of whose value is the same as the length of the padding,
michael@0:  * and that all data is padded.  (Even data that starts out with
michael@0:  * an exact multiple of blocks gets added to it another block,
michael@0:  * all of which is padding.)
michael@0:  *
michael@0:  * XXX I would kind of like to combine this with the function above
michael@0:  * which does decryption, since they have a lot in common.  But the
michael@0:  * tricky parts about padding and filling blocks would be much
michael@0:  * harder to read that way, so I left them separate.  At least for
michael@0:  * now until it is clear that they are right.
michael@0:  */ 
michael@0: SECStatus
michael@0: NSS_CMSCipherContext_Encrypt(NSSCMSCipherContext *cc, unsigned char *output,
michael@0: 		  unsigned int *output_len_p, unsigned int max_output_len,
michael@0: 		  const unsigned char *input, unsigned int input_len,
michael@0: 		  PRBool final)
michael@0: {
michael@0:     int blocks, bsize, padlen, pcount, padsize;
michael@0:     unsigned int max_needed, ifraglen, ofraglen, output_len;
michael@0:     unsigned char *pbuf;
michael@0:     SECStatus rv;
michael@0: 
michael@0:     PORT_Assert (cc->encrypt);
michael@0: 
michael@0:     /*
michael@0:      * Check that we have enough room for the output.  Our caller should
michael@0:      * already handle this; failure is really an internal error (i.e. bug).
michael@0:      */
michael@0:     max_needed = NSS_CMSCipherContext_EncryptLength (cc, input_len, final);
michael@0:     PORT_Assert (max_output_len >= max_needed);
michael@0:     if (max_output_len < max_needed) {
michael@0: 	/* PORT_SetError (XXX); */
michael@0: 	return SECFailure;
michael@0:     }
michael@0: 
michael@0:     bsize = cc->block_size;
michael@0:     padsize = cc->pad_size;
michael@0: 
michael@0:     /*
michael@0:      * When no blocking and padding work to do, we can simply call the
michael@0:      * cipher function and we are done.
michael@0:      */
michael@0:     if (bsize == 0) {
michael@0: 	return (*cc->doit)(cc->cx, output, output_len_p, max_output_len,
michael@0: 			      input, input_len);
michael@0:     }
michael@0: 
michael@0:     pcount = cc->pending_count;
michael@0:     pbuf = cc->pending_buf;
michael@0: 
michael@0:     output_len = 0;
michael@0: 
michael@0:     if (pcount) {
michael@0: 	/*
michael@0: 	 * Try to fill in an entire block, starting with the bytes
michael@0: 	 * we already have saved away.
michael@0: 	 */
michael@0: 	while (input_len && pcount < bsize) {
michael@0: 	    pbuf[pcount++] = *input++;
michael@0: 	    input_len--;
michael@0: 	}
michael@0: 	/*
michael@0: 	 * If we do not have a full block and we know we will be
michael@0: 	 * called again, then we are done for now.
michael@0: 	 */
michael@0: 	if (pcount < bsize && !final) {
michael@0: 	    cc->pending_count = pcount;
michael@0: 	    if (output_len_p != NULL)
michael@0: 		*output_len_p = 0;
michael@0: 	    return SECSuccess;
michael@0: 	}
michael@0: 	/*
michael@0: 	 * If we have a whole block available, encrypt it.
michael@0: 	 */
michael@0: 	if ((padsize == 0) || (pcount % padsize) == 0) {
michael@0: 	    rv = (* cc->doit) (cc->cx, output, &ofraglen, max_output_len,
michael@0: 				pbuf, pcount);
michael@0: 	    if (rv != SECSuccess)
michael@0: 		return rv;
michael@0: 
michael@0: 	    /*
michael@0: 	     * For now anyway, all of our ciphers have the same number of
michael@0: 	     * bytes of output as they do input.  If this ever becomes untrue,
michael@0: 	     * then sec_PKCS7EncryptLength needs to be made smarter!
michael@0: 	     */
michael@0: 	    PORT_Assert (ofraglen == pcount);
michael@0: 
michael@0: 	    /*
michael@0: 	     * Account for the bytes now in output.
michael@0: 	     */
michael@0: 	    max_output_len -= ofraglen;
michael@0: 	    output_len += ofraglen;
michael@0: 	    output += ofraglen;
michael@0: 
michael@0: 	    pcount = 0;
michael@0: 	}
michael@0:     }
michael@0: 
michael@0:     if (input_len) {
michael@0: 	PORT_Assert (pcount == 0);
michael@0: 
michael@0: 	blocks = input_len / bsize;
michael@0: 	ifraglen = blocks * bsize;
michael@0: 
michael@0: 	if (ifraglen) {
michael@0: 	    rv = (* cc->doit) (cc->cx, output, &ofraglen, max_output_len,
michael@0: 				input, ifraglen);
michael@0: 	    if (rv != SECSuccess)
michael@0: 		return rv;
michael@0: 
michael@0: 	    /*
michael@0: 	     * For now anyway, all of our ciphers have the same number of
michael@0: 	     * bytes of output as they do input.  If this ever becomes untrue,
michael@0: 	     * then sec_PKCS7EncryptLength needs to be made smarter!
michael@0: 	     */
michael@0: 	    PORT_Assert (ifraglen == ofraglen);
michael@0: 
michael@0: 	    max_output_len -= ofraglen;
michael@0: 	    output_len += ofraglen;
michael@0: 	    output += ofraglen;
michael@0: 	}
michael@0: 
michael@0: 	pcount = input_len - ifraglen;
michael@0: 	PORT_Assert (pcount < bsize);
michael@0: 	if (pcount)
michael@0: 	    PORT_Memcpy (pbuf, input + ifraglen, pcount);
michael@0:     }
michael@0: 
michael@0:     if (final) {
michael@0: 	padlen = padsize - (pcount % padsize);
michael@0: 	PORT_Memset (pbuf + pcount, padlen, padlen);
michael@0: 	rv = (* cc->doit) (cc->cx, output, &ofraglen, max_output_len,
michael@0: 			    pbuf, pcount+padlen);
michael@0: 	if (rv != SECSuccess)
michael@0: 	    return rv;
michael@0: 
michael@0: 	/*
michael@0: 	 * For now anyway, all of our ciphers have the same number of
michael@0: 	 * bytes of output as they do input.  If this ever becomes untrue,
michael@0: 	 * then sec_PKCS7EncryptLength needs to be made smarter!
michael@0: 	 */
michael@0: 	PORT_Assert (ofraglen == (pcount+padlen));
michael@0: 	output_len += ofraglen;
michael@0:     } else {
michael@0: 	cc->pending_count = pcount;
michael@0:     }
michael@0: 
michael@0:     PORT_Assert (output_len_p != NULL || output_len == 0);
michael@0:     if (output_len_p != NULL)
michael@0: 	*output_len_p = output_len;
michael@0: 
michael@0:     return SECSuccess;
michael@0: }