+ MSBits = (BN_num_bits(rsa->n) - 1) & 0x7;
+ emLen = RSA_size(rsa);
+ if (EM[0] & (0xFF << MSBits)) {
+ RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS_MGF1, RSA_R_FIRST_OCTET_INVALID);
+ goto err;
+ }
+ if (MSBits == 0) {
+ EM++;
+ emLen--;
+ }
+ if (emLen < hLen + 2) {
+ RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS_MGF1, RSA_R_DATA_TOO_LARGE);
+ goto err;
+ }
+ if (sLen > emLen - hLen - 2) { /* sLen can be small negative */
+ RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS_MGF1, RSA_R_DATA_TOO_LARGE);
+ goto err;
+ }
+ if (EM[emLen - 1] != 0xbc) {
+ RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS_MGF1, RSA_R_LAST_OCTET_INVALID);
+ goto err;
+ }
+ maskedDBLen = emLen - hLen - 1;
+ H = EM + maskedDBLen;
+ DB = OPENSSL_malloc(maskedDBLen);
+ if (!DB) {
+ RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS_MGF1, ERR_R_MALLOC_FAILURE);
+ goto err;
+ }
+ if (PKCS1_MGF1(DB, maskedDBLen, H, hLen, mgf1Hash) < 0)
+ goto err;
+ for (i = 0; i < maskedDBLen; i++)
+ DB[i] ^= EM[i];
+ if (MSBits)
+ DB[0] &= 0xFF >> (8 - MSBits);
+ for (i = 0; DB[i] == 0 && i < (maskedDBLen - 1); i++) ;
+ if (DB[i++] != 0x1) {
+ RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS_MGF1, RSA_R_SLEN_RECOVERY_FAILED);
+ goto err;
+ }
+ if (sLen >= 0 && (maskedDBLen - i) != sLen) {
+ RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS_MGF1, RSA_R_SLEN_CHECK_FAILED);
+ goto err;
+ }
+ if (!EVP_DigestInit_ex(&ctx, Hash, NULL)
+ || !EVP_DigestUpdate(&ctx, zeroes, sizeof zeroes)
+ || !EVP_DigestUpdate(&ctx, mHash, hLen))
+ goto err;
+ if (maskedDBLen - i) {
+ if (!EVP_DigestUpdate(&ctx, DB + i, maskedDBLen - i))
+ goto err;
+ }
+ if (!EVP_DigestFinal_ex(&ctx, H_, NULL))
+ goto err;
+ if (memcmp(H_, H, hLen)) {
+ RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS_MGF1, RSA_R_BAD_SIGNATURE);
+ ret = 0;
+ } else
+ ret = 1;