ECDSA Cipher Object

Operations Supported

SignInit(), Sign(), VerifyInit(), and Verify().

Key Encoding

When performing:

>Sign operation: the key is specified as a buffer of ECC_Curve_t followed by Private Key ECC_PrivateKey_t.

>Verify operation: the key is specified as a buffer of ECC_Curve_t followed by Public Key ECC_PublicKey_t.

See also ECDSA Key Structures.

Modes

None

Sign/Verify Parameters

None

ECDSA Key Structures

#define ECC_MAX_MOD_LEN 571
#define ECC_MAX_BUF_LEN ROUND_UP(ECC_MAX_MOD_LEN, 8)/8

typedef enum ECC_FieldType_et {
        ECC_FT_GFP,
        ECC_FT_G2M
        ECC_FT_MON
} ECC_FieldType_t;

Where:

>ECC_FT_GFP: Identifies a curve over a field with an odd prime number of elements.

>ECC_FT_G2M: Identifies a curve over a field of characteristic two (F_2^m).

>ECC_FT_MON: Identifies a curve that uses a Montgomery function.

typedef struct ECC_Point_st {
        unsigned char x[ECC_MAX_BUF_LEN];
        unsigned char y[ECC_MAX_BUF_LEN];
} ECC_Point_t;

Where:

>x: The X coordinate of the point. X is an element of the field over which the curve is defined.

>y: The Y coordinate of the point. Y is an element of the field over which the curve is defined.

typedef struct ECC_Curve_st {
        ECC_FieldType_t fieldType;
        ECC_Point_t base;
        unsigned char modulus[ECC_MAX_BUF_LEN];
        unsigned char a[ECC_MAX_BUF_LEN];
        unsigned char b[ECC_MAX_BUF_LEN];
        unsigned char bpOrder[ECC_MAX_BUF_LEN];
} ECC_Curve_t;

Where:

>fieldType: The field type, over which this curve is defined.

>base: The base point.

>modulus: The curve modulus. This value is the field polynomial for ECC_FT_G2M field types.

>a: The coefficient 'a' in the elliptic curve equation.

>b: The coefficient 'b' in the elliptic curve equation.

>bpOrder: The base point order. This buffer contains a big endian large number regardless of the field type.

typedef struct ECC_PrivateKey_st {

        unsigned char d[ECC_MAX_BUF_LEN];

} ECC_PrivateKey_t;

Where:

>d: The buffer containing the private key. The private key is always a big-endian large number, d, regardless of the field type of the curve.

typedef struct ECC_PublicKey_st {

        ECC_Point_t p;

} ECC_PublicKey_t;

Where:

>p: The point P on the curve, which is calculated from the curve base and the private key.