1 files changed, 98 insertions, 0 deletions
diff --git a/crypto/openssl/providers/implementations/encode_decode/ml_common_codecs.h b/crypto/openssl/providers/implementations/encode_decode/ml_common_codecs.h
new file mode 100644
index 000000000000..4bf618ea0b79
--- /dev/null
+++ b/crypto/openssl/providers/implementations/encode_decode/ml_common_codecs.h
@@ -0,0 +1,98 @@
+/*
+ * Copyright 2025 The OpenSSL Project Authors. All Rights Reserved.
+ *
+ * Licensed under the Apache License 2.0 (the "License").  You may not use
+ * this file except in compliance with the License.  You can obtain a copy
+ * in the file LICENSE in the source distribution or at
+ * https://www.openssl.org/source/license.html
+ */
+
+#ifndef PROV_ML_COMMON_CODECS_H
+# define PROV_ML_COMMON_CODECS_H
+# pragma once
+
+#  include <openssl/e_os2.h>
+#  include "crypto/ml_dsa.h"
+#  include "prov/provider_ctx.h"
+
+ /*-
+  * The DER ASN.1 encoding of ML-DSA and ML-KEM public keys prepends 22 bytes
+  * to the encoded public key:
+  *
+  * - 4 byte outer sequence tag and length
+  * -  2 byte algorithm sequence tag and length
+  * -    2 byte algorithm OID tag and length
+  * -      9 byte algorithm OID (from NIST CSOR OID arc)
+  * -  4 byte bit string tag and length
+  * -    1 bitstring lead byte
+  */
+#  define ML_COMMON_SPKI_OVERHEAD   22
+typedef struct {
+    const uint8_t asn1_prefix[ML_COMMON_SPKI_OVERHEAD];
+} ML_COMMON_SPKI_FMT;
+
+/*-
+* For each parameter set we support a few PKCS#8 input formats, three
+ * corresponding to the "either or both" variants of:
+ *
+ *  ML-DSA-PrivateKey ::= CHOICE {
+ *    seed [0] IMPLICIT OCTET STRING (SIZE (32)),
+ *    expandedKey OCTET STRING (SIZE (2560 | 4032 | 4896)),
+ *    both SEQUENCE {
+ *      seed OCTET STRING (SIZE (32)),
+ *      expandedKey OCTET STRING (SIZE (2560 | 4032 | 4896)) } }
+ *
+ *  ML-KEM-PrivateKey ::= CHOICE {
+ *    seed [0] IMPLICIT OCTET STRING (SIZE (64)),
+ *    expandedKey OCTET STRING (SIZE (1632 | 2400 | 3168)),
+ *    both SEQUENCE {
+ *      seed OCTET STRING (SIZE (64)),
+ *      expandedKey OCTET STRING SIZE ((1632 | 2400 | 3168)) } }
+ *
+ * one more for a historical OQS encoding:
+ *
+ * - OQS private + public key: OCTET STRING
+ *   (The public key is ignored, just as with PKCS#8 v2.)
+ *
+ * and two more that are the minimal IETF non-ASN.1 seed encoding:
+ *
+ * - Bare seed (just the 32 or 64 bytes)
+ * - Bare priv (just the key bytes)
+ *
+ * A length of zero means that particular field is absent.
+ *
+ * The p8_shift is 0 when the top-level tag+length occupy four bytes, 2 when
+ * they occupy two by†es, and 4 when no tag is used at all.
+ */
+#define NUM_PKCS8_FORMATS   6
+
+typedef struct {
+    const char *p8_name;    /* Format name */
+    size_t p8_bytes;        /* Total P8 encoding length */
+    int    p8_shift;        /* 4 - (top-level tag + len) */
+    uint32_t p8_magic;      /* The tag + len value */
+    uint16_t seed_magic;    /* Interior tag + len for the seed */
+    size_t seed_offset;     /* Seed offset from start */
+    size_t seed_length;     /* Seed bytes */
+    uint32_t priv_magic;    /* Interior tag + len for the key */
+    size_t priv_offset;     /* Key offset from start */
+    size_t priv_length;     /* Key bytes */
+    size_t pub_offset;      /* Pubkey offset */
+    size_t pub_length;      /* Pubkey bytes */
+} ML_COMMON_PKCS8_FMT;
+
+typedef struct {
+    const ML_COMMON_SPKI_FMT *spkifmt;
+    const ML_COMMON_PKCS8_FMT *p8fmt;
+} ML_COMMON_CODEC;
+
+typedef struct {
+    const ML_COMMON_PKCS8_FMT *fmt;
+    int pref;
+} ML_COMMON_PKCS8_FMT_PREF;
+
+ML_COMMON_PKCS8_FMT_PREF *
+ossl_ml_common_pkcs8_fmt_order(const char *algorithm_name,
+                               const ML_COMMON_PKCS8_FMT *p8fmt,
+                               const char *direction, const char *formats);
+#endif