/// <summary>
/// Assert that all the <see cref="IdTokenRequirements"/> are met by a JWT ID token for a given point in time.
/// </summary>
/// <param name="required"><see cref="IdTokenRequirements"/> that should be asserted.</param>
/// <param name="rawIDToken">Raw ID token to assert requirements against.</param>
/// <param name="pointInTime">Optional <see cref="DateTime"/> to act as "Now" in order to facilitate unit testing with static tokens.</param>
/// <param name="signatureVerifier">Optional <see cref="ISignatureVerifier"/> to perform signature verification and token extraction. If unspecified
/// <see cref="AsymmetricSignatureVerifier"/> is used against the <paramref name="required"/> Issuer.</param>
/// <exception cref="IdTokenValidationException">Exception thrown if <paramref name="rawIDToken"/> fails to
/// meet the requirements specified by <paramref name="required"/>.
/// </exception>
/// <returns><see cref="Task"/> that will complete when the token is validated.</returns>
internal static async Task AssertTokenMeetsRequirements(this IdTokenRequirements required, string rawIDToken, DateTime?pointInTime = null, ISignatureVerifier signatureVerifier = null)
{
if (string.IsNullOrWhiteSpace(rawIDToken))
{
throw new IdTokenValidationException("ID token is required but missing.");
}
var token = DecodeToken(rawIDToken);
// For now we want to support HS256 + ClientSecret as we just had a major release.
// TODO: In the next major (v4.0) we should remove this condition as well as Auth0ClientOptions.ClientSecret
if (token.SignatureAlgorithm != "HS256")
{
(signatureVerifier ?? await AsymmetricSignatureVerifier.ForJwks(required.Issuer)).VerifySignature(rawIDToken);
}
AssertTokenClaimsMeetRequirements(required, token, pointInTime ?? DateTime.Now);
}
/// <summary>
/// Assert that all the claims within a <see cref="JwtSecurityToken"/> meet the specified <see cref="IdTokenRequirements"/> for a given point in time.
/// </summary>
/// <param name="required"><see cref="IdTokenRequirements"/> that should be asserted.</param>
/// <param name="token"><see cref="JwtSecurityToken"/> to assert requirements against.</param>
/// <param name="pointInTime"><see cref="DateTime"/> to act as "Now" when asserting time-based claims.</param>
/// <exception cref="IdTokenValidationException">Exception thrown if <paramref name="token"/> fails to
/// meet the requirements specified by <paramref name="required"/>.
/// </exception>
public static void AssertClaimsMeetRequirements(IdTokenRequirements required, JwtSecurityToken token, DateTime?pointInTime = null)
{
var epochNow = EpochTime.GetIntDate(pointInTime ?? DateTime.Now);
// Issuer
if (string.IsNullOrWhiteSpace(token.Issuer))
{
throw new IdTokenValidationException("Issuer (iss) claim must be a string present in the ID token.");
}
if (token.Issuer != required.Issuer)
{
throw new IdTokenValidationException($"Issuer (iss) claim mismatch in the ID token; expected \"{required.Issuer}\", found \"{token.Issuer}\".");
}
// Subject
if (string.IsNullOrWhiteSpace(token.Subject))
{
throw new IdTokenValidationException("Subject (sub) claim must be a string present in the ID token.");
}
// Audience
var audienceCount = token.Audiences.Count();
if (audienceCount == 0)
{
throw new IdTokenValidationException("Audience (aud) claim must be a string or array of strings present in the ID token.");
}
if (!token.Audiences.Contains(required.Audience))
{
throw new IdTokenValidationException($"Audience (aud) claim mismatch in the ID token; expected \"{required.Audience}\" but was not one of \"" +
$"{String.Join(", ", token.Audiences)}\".");
}
{
// Expires at
var exp = GetEpoch(token.Claims, JwtRegisteredClaimNames.Exp);
if (exp == null)
{
throw new IdTokenValidationException("Expiration Time (exp) claim must be an integer present in the ID token.");
}
var expiration = exp + required.Leeway.TotalSeconds;
if (epochNow >= expiration)
{
throw new IdTokenValidationException($"Expiration Time (exp) claim error in the ID token; current time ({epochNow}) is after expiration time ({exp}).");
}
}
// Issued at
var iat = GetEpoch(token.Claims, JwtRegisteredClaimNames.Iat);
if (iat == null)
{
throw new IdTokenValidationException("Issued At (iat) claim must be an integer present in the ID token.");
}
// Nonce
if (required.Nonce != null)
{
if (string.IsNullOrWhiteSpace(token.Payload.Nonce))
{
throw new IdTokenValidationException("Nonce (nonce) claim must be a string present in the ID token.");
}
if (token.Payload.Nonce != required.Nonce)
{
throw new IdTokenValidationException($"Nonce (nonce) claim mismatch in the ID token; expected \"{required.Nonce}\", found \"{token.Payload.Nonce}\".");
}
}
// Authorized Party
if (audienceCount > 1)
{
if (string.IsNullOrWhiteSpace(token.Payload.Azp))
{
throw new IdTokenValidationException("Authorized Party (azp) claim must be a string present in the ID token when Audiences (aud) claim has multiple values.");
}
if (token.Payload.Azp != required.Audience)
{
throw new IdTokenValidationException($"Authorized Party (azp) claim mismatch in the ID token; expected \"{required.Audience}\", found \"{token.Payload.Azp}\".");
}
}
// Authentication time
if (required.MaxAge.HasValue)
{
var authTime = GetEpoch(token.Claims, JwtRegisteredClaimNames.AuthTime);
if (!authTime.HasValue)
{
throw new IdTokenValidationException("Authentication Time (auth_time) claim must be an integer present in the ID token when MaxAge specified.");
}
var authValidUntil = (long)(authTime + required.MaxAge.Value.TotalSeconds + required.Leeway.TotalSeconds);
if (epochNow > authValidUntil)
{
throw new IdTokenValidationException($"Authentication Time (auth_time) claim in the ID token indicates that too much time has passed since the last end-user authentication. Current time ({epochNow}) is after last auth at {authValidUntil}.");
}
}
// Organization
if (!string.IsNullOrWhiteSpace(required.Organization))
{
var organization = GetClaimValue(token.Claims, Auth0ClaimNames.Organization);
if (string.IsNullOrWhiteSpace(organization))
{
throw new IdTokenValidationException("Organization claim must be a string present in the ID token.");
}
if (organization != required.Organization)
{
throw new IdTokenValidationException($"Organization claim mismatch in the ID token; expected \"{required.Organization}\", found \"{organization}\".");
}
}
}