diff --git a/src/openvpn/crypto.c b/src/openvpn/crypto.c
index 9f2828a4..78ca4197 100644
--- a/src/openvpn/crypto.c
+++ b/src/openvpn/crypto.c
@@ -820,7 +820,7 @@ init_key_type(struct key_type *kt, const char *ciphername,
 
 /* given a key and key_type, build a key_ctx */
 void
-init_key_ctx(struct key_ctx *ctx, struct key *key,
+init_key_ctx(struct key_ctx *ctx, const struct key *key,
              const struct key_type *kt, int enc,
              const char *prefix)
 {
diff --git a/src/openvpn/crypto.h b/src/openvpn/crypto.h
index 8e2f2b15..fec2eea7 100644
--- a/src/openvpn/crypto.h
+++ b/src/openvpn/crypto.h
@@ -312,7 +312,7 @@ void init_key_type(struct key_type *kt, const char *ciphername,
  * Key context functions
  */
 
-void init_key_ctx(struct key_ctx *ctx, struct key *key,
+void init_key_ctx(struct key_ctx *ctx, const struct key *key,
                   const struct key_type *kt, int enc,
                   const char *prefix);
 
diff --git a/src/openvpn/crypto_backend.h b/src/openvpn/crypto_backend.h
index b7f519b5..567fd9b2 100644
--- a/src/openvpn/crypto_backend.h
+++ b/src/openvpn/crypto_backend.h
@@ -323,7 +323,7 @@ void cipher_ctx_free(cipher_ctx_t *ctx);
  * @param enc           Whether to encrypt or decrypt (either
  *                      \c MBEDTLS_OP_ENCRYPT or \c MBEDTLS_OP_DECRYPT).
  */
-void cipher_ctx_init(cipher_ctx_t *ctx, uint8_t *key, int key_len,
+void cipher_ctx_init(cipher_ctx_t *ctx, const uint8_t *key, int key_len,
                      const cipher_kt_t *kt, int enc);
 
 /**
@@ -391,7 +391,7 @@ const cipher_kt_t *cipher_ctx_get_cipher_kt(const cipher_ctx_t *ctx);
  *
  * @return              \c 0 on failure, \c 1 on success.
  */
-int cipher_ctx_reset(cipher_ctx_t *ctx, uint8_t *iv_buf);
+int cipher_ctx_reset(cipher_ctx_t *ctx, const uint8_t *iv_buf);
 
 /**
  * Updates the given cipher context, providing additional data (AD) for
diff --git a/src/openvpn/crypto_mbedtls.c b/src/openvpn/crypto_mbedtls.c
index 24bc3158..30b51a5f 100644
--- a/src/openvpn/crypto_mbedtls.c
+++ b/src/openvpn/crypto_mbedtls.c
@@ -523,7 +523,7 @@ cipher_ctx_free(mbedtls_cipher_context_t *ctx)
 }
 
 void
-cipher_ctx_init(mbedtls_cipher_context_t *ctx, uint8_t *key, int key_len,
+cipher_ctx_init(mbedtls_cipher_context_t *ctx, const uint8_t *key, int key_len,
                 const mbedtls_cipher_info_t *kt, const mbedtls_operation_t operation)
 {
     ASSERT(NULL != kt && NULL != ctx);
@@ -597,7 +597,7 @@ cipher_ctx_get_cipher_kt(const cipher_ctx_t *ctx)
 }
 
 int
-cipher_ctx_reset(mbedtls_cipher_context_t *ctx, uint8_t *iv_buf)
+cipher_ctx_reset(mbedtls_cipher_context_t *ctx, const uint8_t *iv_buf)
 {
     if (!mbed_ok(mbedtls_cipher_reset(ctx)))
     {
diff --git a/src/openvpn/crypto_openssl.c b/src/openvpn/crypto_openssl.c
index 9cf3355b..138455a4 100644
--- a/src/openvpn/crypto_openssl.c
+++ b/src/openvpn/crypto_openssl.c
@@ -665,7 +665,7 @@ cipher_ctx_free(EVP_CIPHER_CTX *ctx)
 }
 
 void
-cipher_ctx_init(EVP_CIPHER_CTX *ctx, uint8_t *key, int key_len,
+cipher_ctx_init(EVP_CIPHER_CTX *ctx, const uint8_t *key, int key_len,
                 const EVP_CIPHER *kt, int enc)
 {
     ASSERT(NULL != kt && NULL != ctx);
@@ -732,7 +732,7 @@ cipher_ctx_get_cipher_kt(const cipher_ctx_t *ctx)
 
 
 int
-cipher_ctx_reset(EVP_CIPHER_CTX *ctx, uint8_t *iv_buf)
+cipher_ctx_reset(EVP_CIPHER_CTX *ctx, const uint8_t *iv_buf)
 {
     return EVP_CipherInit_ex(ctx, NULL, NULL, NULL, iv_buf, -1);
 }