Add OAEP.

1 files changed, 168 insertions, 0 deletions

diff --git a/crypto/rsa/rsa_oaep.c b/crypto/rsa/rsa_oaep.c
new file mode 100644
index 0000000000..6907ba9969
--- /dev/null
+++ b/crypto/rsa/rsa_oaep.c
@@ -0,0 +1,168 @@
+/* crypto/rsa/rsa_oaep.c */
+/* Written by Ulf Moeller. This software is distributed on an "AS IS"
+   basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. */
+
+/* EME_OAEP as defined in RFC 2437 (PKCS #1 v2.0) */
+
+#include <stdio.h>
+#include "cryptlib.h"
+#include "bn.h"
+#include "rsa.h"
+#include "sha.h"
+#include "rand.h"
+
+int MGF1(unsigned char *mask, long len, unsigned char *seed, long seedlen);
+
+int RSA_padding_add_PKCS1_OAEP(to, tlen, from, flen, param, plen)
+     unsigned char *to;
+     int tlen;
+     unsigned char *from;
+     int flen;
+     unsigned char *param;
+     int plen;
+    {
+    int i, emlen = tlen - 1;
+    unsigned char *db, *seed;
+    unsigned char *dbmask, seedmask[SHA_DIGEST_LENGTH];
+
+    if (flen > emlen - 2 * SHA_DIGEST_LENGTH - 1)
+	{
+	RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_OAEP,
+	       RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE);
+	return (0);
+	}
+
+    if (emlen < 2 * SHA_DIGEST_LENGTH + 1)
+	{
+	RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_OAEP, RSA_R_KEY_SIZE_TOO_SMALL);
+	return (0);
+	}
+    
+    dbmask = Malloc(emlen - SHA_DIGEST_LENGTH);
+    if (dbmask == NULL)
+	{
+	RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_OAEP, ERR_R_MALLOC_FAILURE);
+	return (0);
+	}
+
+    to[0] = 0;
+    seed = to + 1;
+    db = to + SHA_DIGEST_LENGTH + 1;
+
+    SHA1(param, plen, db);
+    memset(db + SHA_DIGEST_LENGTH, 0,
+	   emlen - flen - 2 * SHA_DIGEST_LENGTH - 1);
+    db[emlen - flen - SHA_DIGEST_LENGTH - 1] = 0x01;
+    memcpy(db + emlen - flen - SHA_DIGEST_LENGTH, from, (unsigned int) flen);
+    RAND_bytes(seed, SHA_DIGEST_LENGTH);
+#ifdef PKCS_TESTVECT
+    memcpy(seed,
+	   "\xaa\xfd\x12\xf6\x59\xca\xe6\x34\x89\xb4\x79\xe5\x07\x6d\xde\xc2\xf0\x6c\xb5\x8f",
+	   20);
+#endif
+
+    MGF1(dbmask, emlen - SHA_DIGEST_LENGTH, seed, SHA_DIGEST_LENGTH);
+    for (i = 0; i < emlen - SHA_DIGEST_LENGTH; i++)
+	db[i] ^= dbmask[i];
+
+    MGF1(seedmask, SHA_DIGEST_LENGTH, db, emlen - SHA_DIGEST_LENGTH);
+    for (i = 0; i < SHA_DIGEST_LENGTH; i++)
+	seed[i] ^= seedmask[i];
+
+    Free(dbmask);
+    return (1);
+    }
+
+int RSA_padding_check_PKCS1_OAEP(to, tlen, from, flen, num, param, plen)
+     unsigned char *to;
+     int tlen;
+     unsigned char *from;
+     int flen;
+     int num;
+     unsigned char *param;
+     int plen;
+    {
+    int i, dblen, mlen = -1;
+    unsigned char *maskeddb;
+    unsigned char *db, seed[SHA_DIGEST_LENGTH], phash[SHA_DIGEST_LENGTH];
+
+    if (flen < 2 * SHA_DIGEST_LENGTH + 1)
+	{
+	RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_OAEP, RSA_R_OAEP_DECODING_ERROR);
+	return (-1);
+	}
+
+    dblen = flen - SHA_DIGEST_LENGTH;
+    db = Malloc(dblen);
+    if (db == NULL)
+	{
+	RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_OAEP, ERR_R_MALLOC_FAILURE);
+	return (-1);
+	}
+
+    maskeddb = from + SHA_DIGEST_LENGTH;
+    
+    MGF1(seed, SHA_DIGEST_LENGTH, maskeddb, dblen);
+    for (i = 0; i < SHA_DIGEST_LENGTH; i++)
+	seed[i] ^= from[i];
+  
+    MGF1(db, dblen, seed, SHA_DIGEST_LENGTH);
+    for (i = 0; i < dblen; i++)
+	db[i] ^= maskeddb[i];
+
+    SHA1(param, plen, phash);
+
+    if (memcmp(db, phash, SHA_DIGEST_LENGTH) != 0)
+	RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_OAEP, RSA_R_OAEP_DECODING_ERROR);
+    else
+	{
+	for (i = SHA_DIGEST_LENGTH; i < dblen; i++)
+	    if (db[i] != 0x00)
+		break;
+	if (db[i] != 0x01 || i++ >= dblen)
+	    RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_OAEP,
+		   RSA_R_OAEP_DECODING_ERROR);
+	else
+	    {
+	    mlen = dblen - i;
+	    if (tlen < mlen)
+		{
+		RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_OAEP, RSA_R_DATA_TOO_LARGE);
+		mlen = -1;
+		}
+	    else
+		memcpy(to, db + i, mlen);
+	    }
+	}
+    Free(db);
+    return (mlen);
+    }
+
+int MGF1(unsigned char *mask, long len, unsigned char *seed, long seedlen)
+    {
+    long i, outlen = 0;
+    unsigned char cnt[4];
+    SHA_CTX c;
+    unsigned char md[SHA_DIGEST_LENGTH];
+
+    for (i = 0; outlen < len; i++)
+	{
+	cnt[0] = (i >> 24) & 255, cnt[1] = (i >> 16) & 255,
+	  cnt[2] = (i >> 8) & 255, cnt[3] = i & 255;
+	SHA1_Init(&c);
+	SHA1_Update(&c, seed, seedlen);
+	SHA1_Update(&c, cnt, 4);
+	if (outlen + SHA_DIGEST_LENGTH <= len)
+	    {
+	    SHA1_Final(mask + outlen, &c);
+	    outlen += SHA_DIGEST_LENGTH;
+	    }
+	else
+	    {
+	    SHA1_Final(md, &c);
+	    memcpy(mask + outlen, md, len - outlen);
+	    outlen = len;
+	    }
+	}
+    return (0);
+    }