crypto: add additional query accessors for cipher instances

Adds new methods to allow querying the length of the cipher
key, block size and initialization vectors.

Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>

1 files changed, 37 insertions, 0 deletions

diff --git a/include/crypto/cipher.h b/include/crypto/cipher.h
index b4d714f269..aa51c89f8e 100644
--- a/include/crypto/cipher.h
+++ b/include/crypto/cipher.h
@@ -107,6 +107,43 @@ struct QCryptoCipher {
  */
 bool qcrypto_cipher_supports(QCryptoCipherAlgorithm alg);
 
+/**
+ * qcrypto_cipher_get_block_len:
+ * @alg: the cipher algorithm
+ *
+ * Get the required data block size in bytes. When
+ * encrypting data, it must be a multiple of the
+ * block size.
+ *
+ * Returns: the block size in bytes
+ */
+size_t qcrypto_cipher_get_block_len(QCryptoCipherAlgorithm alg);
+
+
+/**
+ * qcrypto_cipher_get_key_len:
+ * @alg: the cipher algorithm
+ *
+ * Get the required key size in bytes.
+ *
+ * Returns: the key size in bytes
+ */
+size_t qcrypto_cipher_get_key_len(QCryptoCipherAlgorithm alg);
+
+
+/**
+ * qcrypto_cipher_get_iv_len:
+ * @alg: the cipher algorithm
+ * @mode: the cipher mode
+ *
+ * Get the required initialization vector size
+ * in bytes, if one is required.
+ *
+ * Returns: the IV size in bytes, or 0 if no IV is permitted
+ */
+size_t qcrypto_cipher_get_iv_len(QCryptoCipherAlgorithm alg,
+                                 QCryptoCipherMode mode);
+
 
 /**
  * qcrypto_cipher_new: