--- /dev/null
+/* 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) */
+
+/* See Victor Shoup, "OAEP reconsidered," Nov. 2000,
+ * <URL: http://www.shoup.net/papers/oaep.ps.Z>
+ * for problems with the security proof for the
+ * original OAEP scheme, which EME-OAEP is based on.
+ *
+ * A new proof can be found in E. Fujisaki, T. Okamoto,
+ * D. Pointcheval, J. Stern, "RSA-OEAP is Still Alive!",
+ * Dec. 2000, <URL: http://eprint.iacr.org/2000/061/>.
+ * The new proof has stronger requirements for the
+ * underlying permutation: "partial-one-wayness" instead
+ * of one-wayness. For the RSA function, this is
+ * an equivalent notion.
+ */
+
+
+#if !defined(OPENSSL_NO_SHA) && !defined(OPENSSL_NO_SHA1)
+#include <stdio.h>
+#include "cryptlib.h"
+#include <openssl/bn.h>
+#include <openssl/rsa.h>
+#include <openssl/evp.h>
+#include <openssl/rand.h>
+#include <openssl/sha.h>
+
+int MGF1(unsigned char *mask, long len,
+ const unsigned char *seed, long seedlen);
+
+int RSA_padding_add_PKCS1_OAEP(unsigned char *to, int tlen,
+ const unsigned char *from, int flen,
+ const 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 = OPENSSL_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;
+
+ EVP_Digest((void *)param, plen, db, NULL, EVP_sha1(), NULL);
+ 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);
+ if (RAND_bytes(seed, SHA_DIGEST_LENGTH) <= 0)
+ return 0;
+#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];
+
+ OPENSSL_free(dbmask);
+ return 1;
+ }
+
+int RSA_padding_check_PKCS1_OAEP(unsigned char *to, int tlen,
+ const unsigned char *from, int flen, int num,
+ const unsigned char *param, int plen)
+ {
+ int i, dblen, mlen = -1;
+ const unsigned char *maskeddb;
+ int lzero;
+ unsigned char *db = NULL, seed[SHA_DIGEST_LENGTH], phash[SHA_DIGEST_LENGTH];
+ int bad = 0;
+
+ if (--num < 2 * SHA_DIGEST_LENGTH + 1)
+ /* 'num' is the length of the modulus, i.e. does not depend on the
+ * particular ciphertext. */
+ goto decoding_err;
+
+ lzero = num - flen;
+ if (lzero < 0)
+ {
+ /* lzero == -1 */
+
+ /* signalling this error immediately after detection might allow
+ * for side-channel attacks (e.g. timing if 'plen' is huge
+ * -- cf. James H. Manger, "A Chosen Ciphertext Attack on RSA Optimal
+ * Asymmetric Encryption Padding (OAEP) [...]", CRYPTO 2001),
+ * so we use a 'bad' flag */
+ bad = 1;
+ lzero = 0;
+ }
+ maskeddb = from - lzero + SHA_DIGEST_LENGTH;
+
+ dblen = num - SHA_DIGEST_LENGTH;
+ db = OPENSSL_malloc(dblen);
+ if (db == NULL)
+ {
+ RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_OAEP, ERR_R_MALLOC_FAILURE);
+ return -1;
+ }
+
+ MGF1(seed, SHA_DIGEST_LENGTH, maskeddb, dblen);
+ for (i = lzero; i < SHA_DIGEST_LENGTH; i++)
+ seed[i] ^= from[i - lzero];
+
+ MGF1(db, dblen, seed, SHA_DIGEST_LENGTH);
+ for (i = 0; i < dblen; i++)
+ db[i] ^= maskeddb[i];
+
+ EVP_Digest((void *)param, plen, phash, NULL, EVP_sha1(), NULL);
+
+ if (memcmp(db, phash, SHA_DIGEST_LENGTH) != 0 || bad)
+ goto decoding_err;
+ else
+ {
+ for (i = SHA_DIGEST_LENGTH; i < dblen; i++)
+ if (db[i] != 0x00)
+ break;
+ if (db[i] != 0x01 || i++ >= dblen)
+ goto decoding_err;
+ else
+ {
+ /* everything looks OK */
+
+ mlen = dblen - i;
+ if (tlen < mlen)
+ {
+ RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_OAEP, RSA_R_DATA_TOO_LARGE);
+ mlen = -1;
+ }
+ else
+ memcpy(to, db + i, mlen);
+ }
+ }
+ OPENSSL_free(db);
+ return mlen;
+
+decoding_err:
+ /* to avoid chosen ciphertext attacks, the error message should not reveal
+ * which kind of decoding error happened */
+ RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_OAEP, RSA_R_OAEP_DECODING_ERROR);
+ if (db != NULL) OPENSSL_free(db);
+ return -1;
+ }
+
+int MGF1(unsigned char *mask, long len,
+ const unsigned char *seed, long seedlen)
+ {
+ long i, outlen = 0;
+ unsigned char cnt[4];
+ EVP_MD_CTX c;
+ unsigned char md[SHA_DIGEST_LENGTH];
+
+ EVP_MD_CTX_init(&c);
+ for (i = 0; outlen < len; i++)
+ {
+ cnt[0] = (unsigned char)((i >> 24) & 255);
+ cnt[1] = (unsigned char)((i >> 16) & 255);
+ cnt[2] = (unsigned char)((i >> 8)) & 255;
+ cnt[3] = (unsigned char)(i & 255);
+ EVP_DigestInit_ex(&c,EVP_sha1(), NULL);
+ EVP_DigestUpdate(&c, seed, seedlen);
+ EVP_DigestUpdate(&c, cnt, 4);
+ if (outlen + SHA_DIGEST_LENGTH <= len)
+ {
+ EVP_DigestFinal_ex(&c, mask + outlen, NULL);
+ outlen += SHA_DIGEST_LENGTH;
+ }
+ else
+ {
+ EVP_DigestFinal_ex(&c, md, NULL);
+ memcpy(mask + outlen, md, len - outlen);
+ outlen = len;
+ }
+ }
+ EVP_MD_CTX_cleanup(&c);
+ return 0;
+ }
+#endif
projects / bcm963xx.git / blobdiff