DigitalData.Core/DigitalData.Core.Security/RSAKey/RSATokenDescriptor.cs

using DigitalData.Core.Abstractions.Security;
using Microsoft.IdentityModel.Tokens;

namespace DigitalData.Core.Security.RSAKey
{
    /// <summary>
    /// Contains some information which used to create a security token. Designed to abstract <see cref="SecurityTokenDescriptor"/>
    /// </summary>
    public class RSATokenDescriptor : RSAPrivateKey, IAsymmetricTokenDescriptor
    {
        internal string IdSeparator { get; set; } = "_-_";

        private string? _id;

        public override string Id { get => _id ?? $"{Issuer}{IdSeparator}{Audience}"; internal set => _id = value; }

        public string? ApiRoute { get; init; }

        #region SecurityTokenDescriptor Map
        /// <summary>
        /// Gets or sets the value of the 'audience' claim.
        /// </summary>
        public required string Audience { get; set; }

        /// <summary>
        /// Defines the compression algorithm that will be used to compress the JWT token payload.
        /// </summary>
        public string CompressionAlgorithm { get; set; }

        /// <summary>
        /// Gets or sets the <see cref="EncryptingCredentials"/> used to create a encrypted security token.
        /// </summary>
        public EncryptingCredentials EncryptingCredentials { get; set; }

        /// <summary>
        /// Gets or sets the value of the 'expiration' claim. This value should be in UTC.
        /// </summary>
        public DateTime? Expires { get; set; }

        /// <summary>
        /// Gets or sets the issuer of this <see cref="SecurityTokenDescriptor"/>.
        /// </summary>
        public required string Issuer { get; set; }

        /// <summary>
        /// Gets or sets the time the security token was issued. This value should be in UTC.
        /// </summary>
        public DateTime? IssuedAt { get; set; }

        /// <summary>
        /// Gets or sets the notbefore time for the security token. This value should be in UTC.
        /// </summary>
        public DateTime? NotBefore { get; set; }

        /// <summary>
        /// Gets or sets the token type.
        /// <remarks> If provided, this will be added as the value for the 'typ' header parameter. In the case of a JWE, this will be added to both the inner (JWS) and the outer token (JWE) header. By default, the value used is 'JWT'.
        /// If <see cref="AdditionalHeaderClaims"/> also contains 'typ' header claim value, it will override the TokenType provided here.
        /// This value is used only for JWT tokens and not for SAML/SAML2 tokens</remarks>
        /// </summary>
        public string TokenType { get; set; }

        /// <summary>
        /// Gets or sets the <see cref="Dictionary{TKey, TValue}"/> which contains any custom header claims that need to be added to the JWT token header.
        /// The 'alg', 'kid', 'x5t', 'enc', and 'zip' claims are added by default based on the <see cref="SigningCredentials"/>,
        /// <see cref="EncryptingCredentials"/>, and/or <see cref="CompressionAlgorithm"/> provided and SHOULD NOT be included in this dictionary as this
        /// will result in an exception being thrown. 
        /// <remarks> These claims are only added to the outer header (in case of a JWE).</remarks>
        /// </summary>
        public IDictionary<string, object> AdditionalHeaderClaims { get; set; }

        /// <summary>
        /// Gets or sets the <see cref="Dictionary{TKey, TValue}"/> which contains any custom header claims that need to be added to the inner JWT token header.
        /// The 'alg', 'kid', 'x5t', 'enc', and 'zip' claims are added by default based on the <see cref="SigningCredentials"/>,
        /// <see cref="EncryptingCredentials"/>, and/or <see cref="CompressionAlgorithm"/> provided and SHOULD NOT be included in this dictionary as this
        /// will result in an exception being thrown. 
        /// <remarks>
        /// For JsonWebTokenHandler, these claims are merged with <see cref="AdditionalHeaderClaims"/> while adding to the inner JWT header.
        /// </remarks>
        /// </summary>
        public IDictionary<string, object> AdditionalInnerHeaderClaims { get; set; }

        /// <summary>
        /// Gets or sets the <see cref="SigningCredentials"/> used to create a security token.
        /// </summary>
        public SigningCredentials SigningCredentials => _lazySigningCredentials.Value;
        #endregion SecurityTokenDescriptor

        private readonly Lazy<RsaSecurityKey> _lazyRsaSecurityKey;

        public SecurityKey SecurityKey => _lazyRsaSecurityKey.Value;

        private readonly Lazy<SigningCredentials> _lazySigningCredentials;

        /// <summary>
        /// Specifies the signature algorithm to be applied to the <see cref="SigningCredentials"/>.
        /// Default is <see cref="SecurityAlgorithms.RsaSha256"/>.
        /// </summary>
        public string SigningAlgorithm { get; init; } = SecurityAlgorithms.RsaSha256;

        /// <summary>
        /// Optionally specifies the digest algorithm to be applied during the signing process for the <see cref="SigningCredentials"/>.
        /// If not provided, the default algorithm is used.
        /// </summary>
        public string? SigningDigest { get; init; }

#pragma warning disable CS8618 // Non-nullable field must contain a non-null value when exiting constructor. Consider declaring as nullable.
        public RSATokenDescriptor()
#pragma warning restore CS8618 // Non-nullable field must contain a non-null value when exiting constructor. Consider declaring as nullable.
        {
            _lazyRsaSecurityKey = new(() => new RsaSecurityKey(RSA));

            _lazySigningCredentials = new(() => SigningDigest is null
                ? new(SecurityKey, SigningAlgorithm)
                : new(SecurityKey, SigningAlgorithm, SigningDigest));
        }
    }
}