diff --git a/src/gcrypt/cipher.c b/src/gcrypt/cipher.c
index e1f1e057..8920a706 100644
--- a/src/gcrypt/cipher.c
+++ b/src/gcrypt/cipher.c
@@ -227,7 +227,7 @@ static bool cipher_remove_padding(cipher_t *cipher, void *indata, size_t inlen,
 	return true;
 }
 
-bool cipher_encrypt(cipher_t *cipher, void *indata, size_t inlen, void *outdata, size_t *outlen, bool oneshot) {
+bool cipher_encrypt(cipher_t *cipher, const void *indata, size_t inlen, void *outdata, size_t *outlen, bool oneshot) {
 	gcry_error_t err;
 
 	// To be fixed
@@ -240,7 +240,7 @@ bool cipher_encrypt(cipher_t *cipher, void *indata, size_t inlen, void *outdata,
 	return true;
 }
 
-bool cipher_decrypt(cipher_t *cipher, void *indata, size_t inlen, void *outdata, size_t *outlen, bool oneshot) {
+bool cipher_decrypt(cipher_t *cipher, const void *indata, size_t inlen, void *outdata, size_t *outlen, bool oneshot) {
 	gcry_error_t err;
 
 	// To be fixed
diff --git a/src/gcrypt/cipher.h b/src/gcrypt/cipher.h
index 759a5239..593b9857 100644
--- a/src/gcrypt/cipher.h
+++ b/src/gcrypt/cipher.h
@@ -41,8 +41,8 @@ extern void cipher_get_key(const struct cipher *, void *, bool);
 extern bool cipher_set_key(struct cipher *, void *, bool);
 extern bool cipher_set_key_from_rsa(struct cipher *, void *, size_t, bool);
 extern bool cipher_regenerate_key(struct cipher *);
-extern bool cipher_encrypt(struct cipher *, void *indata, size_t inlen, void *outdata, size_t *outlen, bool oneshot);
-extern bool cipher_decrypt(struct cipher *, void *indata, size_t inlen, void *outdata, size_t *outlen, bool oneshot);
+extern bool cipher_encrypt(struct cipher *, const void *indata, size_t inlen, void *outdata, size_t *outlen, bool oneshot);
+extern bool cipher_decrypt(struct cipher *, const void *indata, size_t inlen, void *outdata, size_t *outlen, bool oneshot);
 extern int cipher_get_nid(const struct cipher *);
 extern bool cipher_active(const struct cipher *);
 
diff --git a/src/openssl/cipher.c b/src/openssl/cipher.c
index bf999a21..ccd88195 100644
--- a/src/openssl/cipher.c
+++ b/src/openssl/cipher.c
@@ -131,7 +131,7 @@ bool cipher_regenerate_key(cipher_t *cipher, bool encrypt) {
 	return false;
 }
 
-bool cipher_encrypt(cipher_t *cipher, void *indata, size_t inlen, void *outdata, size_t *outlen, bool oneshot) {
+bool cipher_encrypt(cipher_t *cipher, const void *indata, size_t inlen, void *outdata, size_t *outlen, bool oneshot) {
 	if(oneshot) {
 		int len = *outlen, pad;
 		if(EVP_EncryptInit_ex(&cipher->ctx, NULL, NULL, NULL, NULL)
@@ -152,7 +152,7 @@ bool cipher_encrypt(cipher_t *cipher, void *indata, size_t inlen, void *outdata,
 	return false;
 }
 
-bool cipher_decrypt(cipher_t *cipher, void *indata, size_t inlen, void *outdata, size_t *outlen, bool oneshot) {
+bool cipher_decrypt(cipher_t *cipher, const void *indata, size_t inlen, void *outdata, size_t *outlen, bool oneshot) {
 	if(oneshot) {
 		int len = *outlen, pad;
 		if(EVP_DecryptInit_ex(&cipher->ctx, NULL, NULL, NULL, NULL)
diff --git a/src/openssl/cipher.h b/src/openssl/cipher.h
index 68acb410..d17e2545 100644
--- a/src/openssl/cipher.h
+++ b/src/openssl/cipher.h
@@ -41,8 +41,8 @@ extern void cipher_get_key(const cipher_t *, void *);
 extern bool cipher_set_key(cipher_t *, void *, bool);
 extern bool cipher_set_key_from_rsa(cipher_t *, void *, size_t, bool);
 extern bool cipher_regenerate_key(cipher_t *, bool);
-extern bool cipher_encrypt(cipher_t *, void *indata, size_t inlen, void *outdata, size_t *outlen, bool);
-extern bool cipher_decrypt(cipher_t *, void *indata, size_t inlen, void *outdata, size_t *outlen, bool);
+extern bool cipher_encrypt(cipher_t *, const void *indata, size_t inlen, void *outdata, size_t *outlen, bool);
+extern bool cipher_decrypt(cipher_t *, const void *indata, size_t inlen, void *outdata, size_t *outlen, bool);
 extern int cipher_get_nid(const cipher_t *);
 extern bool cipher_active(const cipher_t *);