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RSA-OAEP decrypt: reorganise code
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@ -654,6 +654,9 @@ int rsa_rsaes_oaep_decrypt( rsa_context *ctx,
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const md_info_t *md_info;
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md_context_t md_ctx;
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/*
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* Parameters sanity checks
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*/
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if( ctx->padding != RSA_PKCS_V21 )
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return( POLARSSL_ERR_RSA_BAD_INPUT_DATA );
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@ -662,6 +665,13 @@ int rsa_rsaes_oaep_decrypt( rsa_context *ctx,
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if( ilen < 16 || ilen > sizeof( buf ) )
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return( POLARSSL_ERR_RSA_BAD_INPUT_DATA );
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md_info = md_info_from_type( ctx->hash_id );
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if( md_info == NULL )
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return( POLARSSL_ERR_RSA_BAD_INPUT_DATA );
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/*
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* RSA operation
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*/
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ret = ( mode == RSA_PUBLIC )
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? rsa_public( ctx, input, buf )
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: rsa_private( ctx, f_rng, p_rng, input, buf );
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@ -669,38 +679,37 @@ int rsa_rsaes_oaep_decrypt( rsa_context *ctx,
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if( ret != 0 )
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return( ret );
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/*
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* Unmask data
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*/
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hlen = md_get_size( md_info );
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md_init_ctx( &md_ctx, md_info );
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/* Generate lHash */
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md( md_info, label, label_len, lhash );
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/* seed: Apply seedMask to maskedSeed */
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mgf_mask( buf + 1, hlen, buf + hlen + 1, ilen - hlen - 1,
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&md_ctx );
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/* DB: Apply dbMask to maskedDB */
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mgf_mask( buf + hlen + 1, ilen - hlen - 1, buf + 1, hlen,
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&md_ctx );
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md_free_ctx( &md_ctx );
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/*
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* Check contents
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*/
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p = buf;
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if( *p++ != 0 )
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return( POLARSSL_ERR_RSA_INVALID_PADDING );
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md_info = md_info_from_type( ctx->hash_id );
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if( md_info == NULL )
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return( POLARSSL_ERR_RSA_BAD_INPUT_DATA );
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p += hlen; /* Skip seed */
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hlen = md_get_size( md_info );
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md_init_ctx( &md_ctx, md_info );
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// Generate lHash
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//
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md( md_info, label, label_len, lhash );
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// seed: Apply seedMask to maskedSeed
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//
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mgf_mask( buf + 1, hlen, buf + hlen + 1, ilen - hlen - 1,
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&md_ctx );
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// DB: Apply dbMask to maskedDB
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//
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mgf_mask( buf + hlen + 1, ilen - hlen - 1, buf + 1, hlen,
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&md_ctx );
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p += hlen;
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md_free_ctx( &md_ctx );
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// Check validity
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//
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/* Check lHash */
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if( memcmp( lhash, p, hlen ) != 0 )
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return( POLARSSL_ERR_RSA_INVALID_PADDING );
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