diff --git a/aead.h b/aead.h
index aa5b51c..06d51aa 100644
--- a/aead.h
+++ b/aead.h
@@ -24,5 +24,6 @@ struct lc_aead_impl {
 	int	(*open)(uint8_t *, size_t *, void *, const uint8_t *, size_t,
 		    const uint8_t *, size_t);
 
+	size_t	  argsz;
 	size_t	  blocklen;
 };
diff --git a/auth.c b/auth.c
index e653976..4d28657 100644
--- a/auth.c
+++ b/auth.c
@@ -54,8 +54,8 @@ lc_auth_ctx_new(const struct lc_auth_impl *impl)
 	ctx = malloc(sizeof(*ctx));
 	if (ctx == NULL)
 		return NULL;
-	if (impl->ctx_new != NULL) {
-		ctx->arg = impl->ctx_new();
+	if (impl->argsz > 0) {
+		ctx->arg = malloc(impl->argsz);
 		if (ctx->arg == NULL) {
 			free(ctx);
 			return NULL;
@@ -70,10 +70,7 @@ lc_auth_ctx_new(const struct lc_auth_impl *impl)
 void
 lc_auth_ctx_free(struct lc_auth_ctx *ctx)
 {
-	if (ctx != NULL) {
-		if (ctx->impl != NULL && ctx->impl->ctx_free != NULL)
-			ctx->impl->ctx_free(ctx->arg);
+	if (ctx != NULL)
 		free(ctx->arg);
-	}
 	free(ctx);
 }
diff --git a/auth.h b/auth.h
index 35924b7..480daa9 100644
--- a/auth.h
+++ b/auth.h
@@ -19,16 +19,14 @@
 
 
 struct lc_auth_impl {
-	int	 (*init)(void *, void *);
-	int	 (*update)(void *, const uint8_t *, size_t);
-	int	 (*final)(void *, uint8_t *, size_t *);
-	int	 (*auth)(uint8_t *, size_t *, void *, const uint8_t *, size_t);
+	int	(*init)(void *, void *);
+	int	(*update)(void *, const uint8_t *, size_t);
+	int	(*final)(void *, uint8_t *, size_t *);
+	int	(*auth)(uint8_t *, size_t *, void *, const uint8_t *, size_t);
 
-	void	*(*ctx_new)(void);
-	void	 (*ctx_free)(void *);
-
-	size_t	   blocklen;
-	size_t	   taglen;
+	size_t	  argsz;
+	size_t	  blocklen;
+	size_t	  taglen;
 };
 
 struct lc_auth_ctx {
diff --git a/auth_hmac.c b/auth_hmac.c
index de65912..3c0c817 100644
--- a/auth_hmac.c
+++ b/auth_hmac.c
@@ -114,12 +114,6 @@ hmac_auth(uint8_t *out, size_t *outlen, void *initparams, const uint8_t *in,
 	    hmac_final(&ctx, out, outlen);
 }
 
-static void *
-hmac_ctx_new(void)
-{
-	return malloc(sizeof(struct hmac_ctx));
-}
-
 
 static struct lc_auth_impl	hmac_impl = {
 	.init = &hmac_init,
@@ -127,9 +121,7 @@ static struct lc_auth_impl	hmac_impl = {
 	.final = &hmac_final,
 	.auth = &hmac_auth,
 
-	.ctx_new = &hmac_ctx_new,
-	.ctx_free = NULL,
-
+	.argsz = sizeof(struct hmac_ctx),
 	.blocklen = 0,
 	.taglen = 0,
 };
diff --git a/auth_poly1305.c b/auth_poly1305.c
index ce4c4c8..9175bc6 100644
--- a/auth_poly1305.c
+++ b/auth_poly1305.c
@@ -150,12 +150,6 @@ poly1305_auth(uint8_t *out, size_t *outlen, void *initparams,
 	    poly1305_final(&ctx, out, outlen);
 }
 
-static void *
-poly1305_ctx_new(void)
-{
-	return malloc(sizeof(struct poly1305_ctx));
-}
-
 
 static struct lc_auth_impl	poly1305_impl = {
 	.init = &poly1305_init,
@@ -163,9 +157,7 @@ static struct lc_auth_impl	poly1305_impl = {
 	.final = &poly1305_final,
 	.auth = &poly1305_auth,
 
-	.ctx_new = &poly1305_ctx_new,
-	.ctx_free = NULL,
-
+	.argsz = sizeof(struct poly1305_ctx),
 	.blocklen = LC_POLY1305_BLOCKLEN,
 	.taglen = LC_POLY1305_TAGLEN,
 };
diff --git a/cipher.c b/cipher.c
index 182c4e7..826dc08 100644
--- a/cipher.c
+++ b/cipher.c
@@ -82,8 +82,8 @@ lc_cipher_ctx_new(const struct lc_cipher_impl *impl)
 	ctx = malloc(sizeof(*ctx));
 	if (ctx == NULL)
 		return NULL;
-	if (impl->ctx_new != NULL) {
-		ctx->arg = impl->ctx_new();
+	if (impl->argsz > 0) {
+		ctx->arg = malloc(impl->argsz);
 		if (ctx->arg == NULL) {
 			free(ctx);
 			return NULL;
@@ -98,10 +98,7 @@ lc_cipher_ctx_new(const struct lc_cipher_impl *impl)
 void
 lc_cipher_ctx_free(struct lc_cipher_ctx *ctx)
 {
-	if (ctx != NULL) {
-		if (ctx->impl != NULL && ctx->impl->ctx_free != NULL)
-			ctx->impl->ctx_free(ctx->arg);
+	if (ctx != NULL)
 		free(ctx->arg);
-	}
 	free(ctx);
 }
diff --git a/cipher.h b/cipher.h
index 497de0a..3846fc7 100644
--- a/cipher.h
+++ b/cipher.h
@@ -19,24 +19,22 @@
 
 
 struct lc_cipher_impl {
-	int	 (*encrypt_init)(void *, void *);
-	int	 (*encrypt_update)(void *, uint8_t *, size_t *,
-		    const uint8_t *, size_t);
-	int	 (*encrypt_final)(void *, uint8_t *, size_t *);
-	int	 (*encrypt)(uint8_t *, size_t *, void *, const uint8_t *,
+	int	(*encrypt_init)(void *, void *);
+	int	(*encrypt_update)(void *, uint8_t *, size_t *, const uint8_t *,
+		    size_t);
+	int	(*encrypt_final)(void *, uint8_t *, size_t *);
+	int	(*encrypt)(uint8_t *, size_t *, void *, const uint8_t *,
 		    size_t);
 
-	int	 (*decrypt_init)(void *, void *);
-	int	 (*decrypt_update)(void *, uint8_t *, size_t *,
-		    const uint8_t *, size_t);
-	int	 (*decrypt_final)(void *, uint8_t *, size_t *);
-	int	 (*decrypt)(uint8_t *, size_t *, void *, const uint8_t *,
+	int	(*decrypt_init)(void *, void *);
+	int	(*decrypt_update)(void *, uint8_t *, size_t *, const uint8_t *,
+		    size_t);
+	int	(*decrypt_final)(void *, uint8_t *, size_t *);
+	int	(*decrypt)(uint8_t *, size_t *, void *, const uint8_t *,
 		    size_t);
 
-	void	*(*ctx_new)(void);
-	void	 (*ctx_free)(void *);
-
-	size_t	   blocklen;
+	size_t	  argsz;
+	size_t	  blocklen;
 };
 
 struct lc_cipher_ctx {
diff --git a/cipher_chacha20.c b/cipher_chacha20.c
index d8e9b83..18c7188 100644
--- a/cipher_chacha20.c
+++ b/cipher_chacha20.c
@@ -209,12 +209,6 @@ chacha20_anycrypt(uint8_t *out, size_t *outlen, void *initparams,
 	return rc;
 }
 
-static void *
-chacha20_ctx_new(void)
-{
-	return malloc(sizeof(struct chacha20_ctx));
-}
-
 
 static struct lc_cipher_impl	chacha20_impl = {
 	.encrypt_init = &chacha20_anycrypt_init,
@@ -227,9 +221,7 @@ static struct lc_cipher_impl	chacha20_impl = {
 	.decrypt_final = &chacha20_anycrypt_final,
 	.decrypt = &chacha20_anycrypt,
 
-	.ctx_new = &chacha20_ctx_new,
-	.ctx_free = NULL,
-
+	.argsz = sizeof(struct chacha20_ctx),
 	.blocklen = LC_CHACHA20_BLOCKLEN,
 };
 
@@ -244,9 +236,7 @@ static struct lc_cipher_impl	xchacha20_impl = {
 	.decrypt_final = &chacha20_anycrypt_final,
 	.decrypt = &chacha20_anycrypt,
 
-	.ctx_new = &chacha20_ctx_new,
-	.ctx_free = NULL,
-
+	.argsz = sizeof(struct chacha20_ctx),
 	.blocklen = LC_XCHACHA20_BLOCKLEN,
 };
 
diff --git a/hash.c b/hash.c
index 5226069..22aee66 100644
--- a/hash.c
+++ b/hash.c
@@ -54,8 +54,8 @@ lc_hash_ctx_new(const struct lc_hash_impl *impl)
 	ctx = malloc(sizeof(*ctx));
 	if (ctx == NULL)
 		return NULL;
-	if (impl->ctx_new != NULL) {
-		ctx->arg = impl->ctx_new();
+	if (impl->argsz > 0) {
+		ctx->arg = malloc(impl->argsz);
 		if (ctx->arg == NULL) {
 			free(ctx);
 			return NULL;
@@ -70,10 +70,7 @@ lc_hash_ctx_new(const struct lc_hash_impl *impl)
 void
 lc_hash_ctx_free(struct lc_hash_ctx *ctx)
 {
-	if (ctx != NULL) {
-		if (ctx->impl != NULL && ctx->impl->ctx_free != NULL)
-			ctx->impl->ctx_free(ctx->arg);
+	if (ctx != NULL)
 		free(ctx->arg);
-	}
 	free(ctx);
 }
diff --git a/hash.h b/hash.h
index 16989fc..7ef72de 100644
--- a/hash.h
+++ b/hash.h
@@ -19,16 +19,14 @@
 
 
 struct lc_hash_impl {
-	int	 (*init)(void *);
-	int	 (*update)(void *, const uint8_t *, size_t);
-	int	 (*final)(void *, uint8_t *, size_t *);
-	int	 (*hash)(uint8_t *, size_t *, const uint8_t *, size_t);
+	int	(*init)(void *);
+	int	(*update)(void *, const uint8_t *, size_t);
+	int	(*final)(void *, uint8_t *, size_t *);
+	int	(*hash)(uint8_t *, size_t *, const uint8_t *, size_t);
 
-	void	*(*ctx_new)(void);
-	void	 (*ctx_free)(void *);
-
-	size_t	   blocklen;
-	size_t	   hashlen;
+	size_t	  argsz;
+	size_t	  blocklen;
+	size_t	  hashlen;
 };
 
 struct lc_hash_ctx {
diff --git a/hash_sha224_sha256.c b/hash_sha224_sha256.c
index ea7760d..8ddb377 100644
--- a/hash_sha224_sha256.c
+++ b/hash_sha224_sha256.c
@@ -251,12 +251,6 @@ sha256_hash(uint8_t *out, size_t *outlen, const uint8_t *in, size_t inlen)
 	    sha256_final(&ctx, out, outlen);
 }
 
-static void *
-sha224_sha256_ctx_new(void)
-{
-	return malloc(sizeof(struct sha256_ctx));
-}
-
 
 static struct lc_hash_impl	sha224_impl = {
 	.init = &sha224_init,
@@ -264,9 +258,7 @@ static struct lc_hash_impl	sha224_impl = {
 	.final = &sha224_final,
 	.hash = &sha224_hash,
 
-	.ctx_new = &sha224_sha256_ctx_new,
-	.ctx_free = NULL,
-
+	.argsz = sizeof(struct sha256_ctx),
 	.blocklen = LC_SHA224_BLOCKLEN,
 	.hashlen = LC_SHA224_HASHLEN,
 };
@@ -277,9 +269,7 @@ static struct lc_hash_impl	sha256_impl = {
 	.final = &sha256_final,
 	.hash = &sha256_hash,
 
-	.ctx_new = &sha224_sha256_ctx_new,
-	.ctx_free = NULL,
-
+	.argsz = sizeof(struct sha256_ctx),
 	.blocklen = LC_SHA256_BLOCKLEN,
 	.hashlen = LC_SHA256_HASHLEN,
 };
diff --git a/hash_sha384_sha512.c b/hash_sha384_sha512.c
index f63f657..66bc6be 100644
--- a/hash_sha384_sha512.c
+++ b/hash_sha384_sha512.c
@@ -256,12 +256,6 @@ sha512_hash(uint8_t *out, size_t *outlen, const uint8_t *in, size_t inlen)
 	    sha512_final(&ctx, out, outlen);
 }
 
-static void *
-sha384_sha512_ctx_new(void)
-{
-	return malloc(sizeof(struct sha512_ctx));
-}
-
 
 static struct lc_hash_impl	sha384_impl = {
 	.init = &sha384_init,
@@ -269,9 +263,7 @@ static struct lc_hash_impl	sha384_impl = {
 	.final = &sha384_final,
 	.hash = &sha384_hash,
 
-	.ctx_new = &sha384_sha512_ctx_new,
-	.ctx_free = NULL,
-
+	.argsz = sizeof(struct sha512_ctx),
 	.blocklen = LC_SHA384_BLOCKLEN,
 	.hashlen = LC_SHA384_HASHLEN,
 };
@@ -282,9 +274,7 @@ static struct lc_hash_impl	sha512_impl = {
 	.final = &sha512_final,
 	.hash = &sha512_hash,
 
-	.ctx_new = &sha384_sha512_ctx_new,
-	.ctx_free = NULL,
-
+	.argsz = sizeof(struct sha512_ctx),
 	.blocklen = LC_SHA512_BLOCKLEN,
 	.hashlen = LC_SHA512_HASHLEN,
 };