1 files changed, 85 insertions, 0 deletions
diff --git a/src/rexmpp_digest.h b/src/rexmpp_digest.h
new file mode 100644
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--- /dev/null
+++ b/src/rexmpp_digest.h
@@ -0,0 +1,85 @@
+/**
+   @file rexmpp_digest.h
+   @brief Cryptographic functions
+   @author defanor <defanor@uberspace.net>
+   @date 2023
+   @copyright MIT license.
+*/
+
+#ifndef REXMPP_DIGEST_H
+#define REXMPP_DIGEST_H
+
+typedef enum {
+  REXMPP_DIGEST_SHA1,
+  REXMPP_DIGEST_SHA256,
+  REXMPP_DIGEST_SHA3_256
+} rexmpp_digest_algorithm;
+
+
+#if defined(HAVE_GCRYPT)
+#include <gcrypt.h>
+typedef gcry_md_hd_t rexmpp_digest_t;
+#elif defined(HAVE_NETTLE)
+#include <nettle/nettle-meta.h>
+struct rexmpp_digest {
+  const struct nettle_hash *nh;
+  void *nh_ctx;
+};
+typedef struct rexmpp_digest rexmpp_digest_t;
+#elif defined(HAVE_OPENSSL)
+#include <openssl/evp.h>
+typedef EVP_MD_CTX* rexmpp_digest_t;
+#endif
+
+/**
+   @brief Finds the digest length for a given algorithm.
+   @param[in] algo An algorithm.
+   @returns Digest length in bytes.
+*/
+size_t rexmpp_digest_len (rexmpp_digest_algorithm algo);
+
+/**
+   @brief Computes a digest for a buffer.
+   @param[in] algo An algorithm.
+   @param[in] in Input data.
+   @param[in] in_len Input data length.
+   @param[out] out Output buffer.
+   @param[in] out_len Output buffer length.
+   @returns 0 on success, non-zero on failure.
+*/
+int rexmpp_digest_buffer (rexmpp_digest_algorithm algo,
+                          const void *in,
+                          size_t in_len,
+                          void *out,
+                          size_t out_len);
+
+/**
+   @brief Initializes a digest context.
+   @param[out] ctx Pointer to an allocated ::rexmpp_digest_t context
+   to initialize.
+   @param[in] algo An algorithm to use.
+   @returns 0 on success, non-zero on failure.
+*/
+int rexmpp_digest_init (rexmpp_digest_t *ctx, rexmpp_digest_algorithm algo);
+
+/**
+   @brief Updates a digest computation.
+   @param[in,out] ctx Context pointer.
+   @param[in] in Input data.
+   @param[in] len Length of the input buffer.
+   @returns 0 on success, non-zero on failure.
+*/
+int rexmpp_digest_update (rexmpp_digest_t *ctx, const void *in, size_t len);
+
+/**
+   @brief Finishes a digest computation, freeing the context and
+   providing the output.
+   @param[in,out] ctx Context pointer.
+   @param[out] out A place to write the computed digest into, can be
+   NULL to just free the context.
+   @param[in] len Length of the allocated output buffer.
+   @returns 0 on success, non-zero on failure.
+*/
+int rexmpp_digest_finish (rexmpp_digest_t *ctx, void *out, size_t len);
+
+#endif