1 /**
2  * \file pkwrite.h
3  *
4  * \brief Internal defines shared by the PK write module
5  */
6 /*
7  *  Copyright The Mbed TLS Contributors
8  *  SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
9  */
10 
11 #ifndef MBEDTLS_PK_WRITE_H
12 #define MBEDTLS_PK_WRITE_H
13 
14 #include "mbedtls/build_info.h"
15 
16 #include "mbedtls/pk.h"
17 
18 #if defined(MBEDTLS_USE_PSA_CRYPTO)
19 #include "psa/crypto.h"
20 #endif /* MBEDTLS_USE_PSA_CRYPTO */
21 
22 /*
23  * Max sizes of key per types. Shown as tag + len (+ content).
24  */
25 
26 #if defined(MBEDTLS_RSA_C)
27 /*
28  * RSA public keys:
29  *  SubjectPublicKeyInfo  ::=  SEQUENCE  {          1 + 3
30  *       algorithm            AlgorithmIdentifier,  1 + 1 (sequence)
31  *                                                + 1 + 1 + 9 (rsa oid)
32  *                                                + 1 + 1 (params null)
33  *       subjectPublicKey     BIT STRING }          1 + 3 + (1 + below)
34  *  RSAPublicKey ::= SEQUENCE {                     1 + 3
35  *      modulus           INTEGER,  -- n            1 + 3 + MPI_MAX + 1
36  *      publicExponent    INTEGER   -- e            1 + 3 + MPI_MAX + 1
37  *  }
38  */
39 #define MBEDTLS_PK_RSA_PUB_DER_MAX_BYTES    (38 + 2 * MBEDTLS_MPI_MAX_SIZE)
40 
41 /*
42  * RSA private keys:
43  *  RSAPrivateKey ::= SEQUENCE {                    1 + 3
44  *      version           Version,                  1 + 1 + 1
45  *      modulus           INTEGER,                  1 + 3 + MPI_MAX + 1
46  *      publicExponent    INTEGER,                  1 + 3 + MPI_MAX + 1
47  *      privateExponent   INTEGER,                  1 + 3 + MPI_MAX + 1
48  *      prime1            INTEGER,                  1 + 3 + MPI_MAX / 2 + 1
49  *      prime2            INTEGER,                  1 + 3 + MPI_MAX / 2 + 1
50  *      exponent1         INTEGER,                  1 + 3 + MPI_MAX / 2 + 1
51  *      exponent2         INTEGER,                  1 + 3 + MPI_MAX / 2 + 1
52  *      coefficient       INTEGER,                  1 + 3 + MPI_MAX / 2 + 1
53  *      otherPrimeInfos   OtherPrimeInfos OPTIONAL  0 (not supported)
54  *  }
55  */
56 #define MBEDTLS_MPI_MAX_SIZE_2  (MBEDTLS_MPI_MAX_SIZE / 2 + \
57                                  MBEDTLS_MPI_MAX_SIZE % 2)
58 #define MBEDTLS_PK_RSA_PRV_DER_MAX_BYTES    (47 + 3 * MBEDTLS_MPI_MAX_SIZE \
59                                              + 5 * MBEDTLS_MPI_MAX_SIZE_2)
60 
61 #else /* MBEDTLS_RSA_C */
62 
63 #define MBEDTLS_PK_RSA_PUB_DER_MAX_BYTES   0
64 #define MBEDTLS_PK_RSA_PRV_DER_MAX_BYTES   0
65 
66 #endif /* MBEDTLS_RSA_C */
67 
68 #if defined(MBEDTLS_PK_HAVE_ECC_KEYS)
69 
70 /* Find the maximum number of bytes necessary to store an EC point. When USE_PSA
71  * is defined this means looking for the maximum between PSA and built-in
72  * supported curves. */
73 #if defined(MBEDTLS_USE_PSA_CRYPTO)
74 #define MBEDTLS_PK_MAX_ECC_BYTES   (PSA_BITS_TO_BYTES(PSA_VENDOR_ECC_MAX_CURVE_BITS) > \
75                                     MBEDTLS_ECP_MAX_BYTES ? \
76                                     PSA_BITS_TO_BYTES(PSA_VENDOR_ECC_MAX_CURVE_BITS) : \
77                                     MBEDTLS_ECP_MAX_BYTES)
78 #else /* MBEDTLS_USE_PSA_CRYPTO */
79 #define MBEDTLS_PK_MAX_ECC_BYTES   MBEDTLS_ECP_MAX_BYTES
80 #endif /* MBEDTLS_USE_PSA_CRYPTO */
81 
82 /*
83  * EC public keys:
84  *  SubjectPublicKeyInfo  ::=  SEQUENCE  {      1 + 2
85  *    algorithm         AlgorithmIdentifier,    1 + 1 (sequence)
86  *                                            + 1 + 1 + 7 (ec oid)
87  *                                            + 1 + 1 + 9 (namedCurve oid)
88  *    subjectPublicKey  BIT STRING              1 + 2 + 1               [1]
89  *                                            + 1 (point format)        [1]
90  *                                            + 2 * ECP_MAX (coords)    [1]
91  *  }
92  */
93 #define MBEDTLS_PK_ECP_PUB_DER_MAX_BYTES    (30 + 2 * MBEDTLS_PK_MAX_ECC_BYTES)
94 
95 /*
96  * EC private keys:
97  * ECPrivateKey ::= SEQUENCE {                  1 + 2
98  *      version        INTEGER ,                1 + 1 + 1
99  *      privateKey     OCTET STRING,            1 + 1 + ECP_MAX
100  *      parameters [0] ECParameters OPTIONAL,   1 + 1 + (1 + 1 + 9)
101  *      publicKey  [1] BIT STRING OPTIONAL      1 + 2 + [1] above
102  *    }
103  */
104 #define MBEDTLS_PK_ECP_PRV_DER_MAX_BYTES    (29 + 3 * MBEDTLS_PK_MAX_ECC_BYTES)
105 
106 #else /* MBEDTLS_PK_HAVE_ECC_KEYS */
107 
108 #define MBEDTLS_PK_ECP_PUB_DER_MAX_BYTES   0
109 #define MBEDTLS_PK_ECP_PRV_DER_MAX_BYTES   0
110 
111 #endif /* MBEDTLS_PK_HAVE_ECC_KEYS */
112 #endif /* MBEDTLS_PK_WRITE_H */
113