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gpg: Clean up ECDH code path (4).
* g10/ecdh.c (prepare_ecdh_with_shared_point): New. (pk_ecdh_encrypt_with_shared_point): Fixing error paths for closing the cipher handle, use prepare_ecdh_with_shared_point. Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>
This commit is contained in:
NIIBE Yutaka
parent
80c02d13d9
commit
64d93271bf
311
g10/ecdh.c
311
g10/ecdh.c
@ -209,19 +209,13 @@ derive_kek (size_t kek_size,
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}
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/* Encrypts/decrypts DATA using a key derived from the ECC shared
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point SHARED_MPI using the FIPS SP 800-56A compliant method
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key_derivation+key_wrapping. If IS_ENCRYPT is true the function
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encrypts; if false, it decrypts. PKEY is the public key and PK_FP
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the fingerprint of this public key. On success the result is
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stored at R_RESULT; on failure NULL is stored at R_RESULT and an
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error code returned. */
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gpg_error_t
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pk_ecdh_encrypt_with_shared_point (int is_encrypt, gcry_mpi_t shared_mpi,
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const byte pk_fp[MAX_FINGERPRINT_LEN],
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gcry_mpi_t data, gcry_mpi_t *pkey,
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gcry_mpi_t *r_result)
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/* Prepare ECDH using SHARED_MPI, PK_FP fingerprint, and PKEY array.
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Returns the cipher handle in R_HD, which needs to be closed by
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the caller. */
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static gpg_error_t
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prepare_ecdh_with_shared_point (gcry_mpi_t shared_mpi,
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const byte pk_fp[MAX_FINGERPRINT_LEN],
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gcry_mpi_t *pkey, gcry_cipher_hd_t *r_hd)
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{
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gpg_error_t err;
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byte *secret_x;
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@ -234,8 +228,9 @@ pk_ecdh_encrypt_with_shared_point (int is_encrypt, gcry_mpi_t shared_mpi,
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unsigned char kdf_params[256];
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size_t kdf_params_size;
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size_t kek_size;
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gcry_cipher_hd_t hd;
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*r_result = NULL;
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*r_hd = NULL;
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if (!gcry_mpi_get_flag (pkey[2], GCRYMPI_FLAG_OPAQUE))
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return gpg_error (GPG_ERR_BUG);
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@ -311,159 +306,183 @@ pk_ecdh_encrypt_with_shared_point (int is_encrypt, gcry_mpi_t shared_mpi,
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}
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/* And, finally, aeswrap with key secret_x. */
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{
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gcry_cipher_hd_t hd;
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size_t nbytes;
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err = gcry_cipher_open (&hd, kdf_encr_algo, GCRY_CIPHER_MODE_AESWRAP, 0);
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if (err)
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{
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log_error ("ecdh failed to initialize AESWRAP: %s\n",
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gpg_strerror (err));
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xfree (secret_x);
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return err;
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}
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byte *data_buf;
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int data_buf_size;
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err = gcry_cipher_setkey (hd, secret_x, kek_size);
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xfree (secret_x);
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secret_x = NULL;
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if (err)
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{
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gcry_cipher_close (hd);
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log_error ("ecdh failed in gcry_cipher_setkey: %s\n",
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gpg_strerror (err));
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}
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else
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*r_hd = hd;
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gcry_mpi_t result;
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return err;
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}
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err = gcry_cipher_open (&hd, kdf_encr_algo, GCRY_CIPHER_MODE_AESWRAP, 0);
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if (err)
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{
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log_error ("ecdh failed to initialize AESWRAP: %s\n",
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gpg_strerror (err));
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xfree (secret_x);
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return err;
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}
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/* Encrypts/decrypts DATA using a key derived from the ECC shared
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point SHARED_MPI using the FIPS SP 800-56A compliant method
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key_derivation+key_wrapping. If IS_ENCRYPT is true the function
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encrypts; if false, it decrypts. PKEY is the public key and PK_FP
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the fingerprint of this public key. On success the result is
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stored at R_RESULT; on failure NULL is stored at R_RESULT and an
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error code returned. */
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gpg_error_t
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pk_ecdh_encrypt_with_shared_point (int is_encrypt, gcry_mpi_t shared_mpi,
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const byte pk_fp[MAX_FINGERPRINT_LEN],
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gcry_mpi_t data, gcry_mpi_t *pkey,
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gcry_mpi_t *r_result)
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{
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gpg_error_t err;
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gcry_cipher_hd_t hd;
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size_t nbytes;
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byte *data_buf;
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int data_buf_size;
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gcry_mpi_t result;
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err = gcry_cipher_setkey (hd, secret_x, kek_size);
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xfree (secret_x);
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secret_x = NULL;
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if (err)
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{
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gcry_cipher_close (hd);
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log_error ("ecdh failed in gcry_cipher_setkey: %s\n",
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gpg_strerror (err));
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return err;
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}
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*r_result = NULL;
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data_buf_size = (gcry_mpi_get_nbits(data)+7)/8;
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if ((data_buf_size & 7) != (is_encrypt ? 0 : 1))
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{
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log_error ("can't use a shared secret of %d bytes for ecdh\n",
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data_buf_size);
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return gpg_error (GPG_ERR_BAD_DATA);
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}
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err = prepare_ecdh_with_shared_point (shared_mpi, pk_fp, pkey, &hd);
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if (err)
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return err;
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data_buf = xtrymalloc_secure( 1 + 2*data_buf_size + 8);
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if (!data_buf)
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{
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err = gpg_error_from_syserror ();
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gcry_cipher_close (hd);
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return err;
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}
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data_buf_size = (gcry_mpi_get_nbits(data)+7)/8;
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if ((data_buf_size & 7) != (is_encrypt ? 0 : 1))
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{
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log_error ("can't use a shared secret of %d bytes for ecdh\n",
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data_buf_size);
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gcry_cipher_close (hd);
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return gpg_error (GPG_ERR_BAD_DATA);
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}
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if (is_encrypt)
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{
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byte *in = data_buf+1+data_buf_size+8;
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data_buf = xtrymalloc_secure( 1 + 2*data_buf_size + 8);
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if (!data_buf)
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{
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err = gpg_error_from_syserror ();
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gcry_cipher_close (hd);
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return err;
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}
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/* Write data MPI into the end of data_buf. data_buf is size
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aeswrap data. */
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err = gcry_mpi_print (GCRYMPI_FMT_USG, in,
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data_buf_size, &nbytes, data/*in*/);
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if (err)
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{
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log_error ("ecdh failed to export DEK: %s\n", gpg_strerror (err));
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gcry_cipher_close (hd);
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xfree (data_buf);
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return err;
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}
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if (is_encrypt)
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{
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byte *in = data_buf+1+data_buf_size+8;
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if (DBG_CRYPTO)
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log_printhex (in, data_buf_size, "ecdh encrypting :");
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/* Write data MPI into the end of data_buf. data_buf is size
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aeswrap data. */
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err = gcry_mpi_print (GCRYMPI_FMT_USG, in,
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data_buf_size, &nbytes, data/*in*/);
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if (err)
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{
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log_error ("ecdh failed to export DEK: %s\n", gpg_strerror (err));
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gcry_cipher_close (hd);
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xfree (data_buf);
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return err;
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}
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err = gcry_cipher_encrypt (hd, data_buf+1, data_buf_size+8,
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in, data_buf_size);
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memset (in, 0, data_buf_size);
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gcry_cipher_close (hd);
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if (err)
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{
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log_error ("ecdh failed in gcry_cipher_encrypt: %s\n",
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gpg_strerror (err));
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xfree (data_buf);
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return err;
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}
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data_buf[0] = data_buf_size+8;
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if (DBG_CRYPTO)
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log_printhex (in, data_buf_size, "ecdh encrypting :");
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if (DBG_CRYPTO)
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log_printhex (data_buf+1, data_buf[0], "ecdh encrypted to:");
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err = gcry_cipher_encrypt (hd, data_buf+1, data_buf_size+8,
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in, data_buf_size);
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memset (in, 0, data_buf_size);
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gcry_cipher_close (hd);
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if (err)
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{
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log_error ("ecdh failed in gcry_cipher_encrypt: %s\n",
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gpg_strerror (err));
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xfree (data_buf);
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return err;
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}
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data_buf[0] = data_buf_size+8;
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result = gcry_mpi_set_opaque (NULL, data_buf, 8 * (1+data_buf[0]));
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if (!result)
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{
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err = gpg_error_from_syserror ();
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xfree (data_buf);
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log_error ("ecdh failed to create an MPI: %s\n",
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gpg_strerror (err));
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return err;
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}
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if (DBG_CRYPTO)
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log_printhex (data_buf+1, data_buf[0], "ecdh encrypted to:");
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*r_result = result;
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}
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else
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{
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byte *in;
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const void *p;
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result = gcry_mpi_set_opaque (NULL, data_buf, 8 * (1+data_buf[0]));
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if (!result)
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{
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err = gpg_error_from_syserror ();
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xfree (data_buf);
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log_error ("ecdh failed to create an MPI: %s\n",
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gpg_strerror (err));
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return err;
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}
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p = gcry_mpi_get_opaque (data, &nbits);
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nbytes = (nbits+7)/8;
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if (!p || nbytes > data_buf_size || !nbytes)
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{
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xfree (data_buf);
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return gpg_error (GPG_ERR_BAD_MPI);
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}
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memcpy (data_buf, p, nbytes);
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if (data_buf[0] != nbytes-1)
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{
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log_error ("ecdh inconsistent size\n");
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xfree (data_buf);
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return gpg_error (GPG_ERR_BAD_MPI);
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}
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in = data_buf+data_buf_size;
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data_buf_size = data_buf[0];
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*r_result = result;
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}
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else
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{
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byte *in;
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const void *p;
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unsigned int nbits;
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if (DBG_CRYPTO)
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log_printhex (data_buf+1, data_buf_size, "ecdh decrypting :");
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p = gcry_mpi_get_opaque (data, &nbits);
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nbytes = (nbits+7)/8;
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if (!p || nbytes > data_buf_size || !nbytes)
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{
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xfree (data_buf);
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gcry_cipher_close (hd);
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return gpg_error (GPG_ERR_BAD_MPI);
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}
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memcpy (data_buf, p, nbytes);
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if (data_buf[0] != nbytes-1)
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{
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log_error ("ecdh inconsistent size\n");
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xfree (data_buf);
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gcry_cipher_close (hd);
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return gpg_error (GPG_ERR_BAD_MPI);
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}
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in = data_buf+data_buf_size;
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data_buf_size = data_buf[0];
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err = gcry_cipher_decrypt (hd, in, data_buf_size, data_buf+1,
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data_buf_size);
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gcry_cipher_close (hd);
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if (err)
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{
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log_error ("ecdh failed in gcry_cipher_decrypt: %s\n",
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gpg_strerror (err));
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xfree (data_buf);
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return err;
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}
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if (DBG_CRYPTO)
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log_printhex (data_buf+1, data_buf_size, "ecdh decrypting :");
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data_buf_size -= 8;
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err = gcry_cipher_decrypt (hd, in, data_buf_size, data_buf+1,
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data_buf_size);
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gcry_cipher_close (hd);
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if (err)
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{
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log_error ("ecdh failed in gcry_cipher_decrypt: %s\n",
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gpg_strerror (err));
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xfree (data_buf);
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return err;
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}
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if (DBG_CRYPTO)
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log_printhex (in, data_buf_size, "ecdh decrypted to :");
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data_buf_size -= 8;
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/* Padding is removed later. */
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/* if (in[data_buf_size-1] > 8 ) */
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/* { */
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/* log_error ("ecdh failed at decryption: invalid padding." */
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/* " 0x%02x > 8\n", in[data_buf_size-1] ); */
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/* return gpg_error (GPG_ERR_BAD_KEY); */
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/* } */
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if (DBG_CRYPTO)
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log_printhex (in, data_buf_size, "ecdh decrypted to :");
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err = gcry_mpi_scan (&result, GCRYMPI_FMT_USG, in, data_buf_size, NULL);
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xfree (data_buf);
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if (err)
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{
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log_error ("ecdh failed to create a plain text MPI: %s\n",
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gpg_strerror (err));
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return err;
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}
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/* Padding is removed later. */
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/* if (in[data_buf_size-1] > 8 ) */
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/* { */
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/* log_error ("ecdh failed at decryption: invalid padding." */
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/* " 0x%02x > 8\n", in[data_buf_size-1] ); */
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/* return gpg_error (GPG_ERR_BAD_KEY); */
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/* } */
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*r_result = result;
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}
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}
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err = gcry_mpi_scan (&result, GCRYMPI_FMT_USG, in, data_buf_size, NULL);
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xfree (data_buf);
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if (err)
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{
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log_error ("ecdh failed to create a plain text MPI: %s\n",
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gpg_strerror (err));
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return err;
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}
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*r_result = result;
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}
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return err;
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}
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