Add support for SAML2 relying party registration's decryption credentials

Closes gh-23705

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/security/saml2/Saml2RelyingPartyProperties.java

@@ -63,6 +63,8 @@ public class Saml2RelyingPartyProperties {
 
 		private final Signing signing = new Signing();
 
+		private final Decryption decryption = new Decryption();
+
 		/**
 		 * Remote SAML Identity Provider.
 		 */
@@ -84,6 +86,10 @@ public class Saml2RelyingPartyProperties {
 			return this.signing;
 		}
 
+		public Decryption getDecryption() {
+			return this.decryption;
+		}
+
 		public Identityprovider getIdentityprovider() {
 			return this.identityprovider;
 		}
@@ -123,8 +129,7 @@ public class Saml2RelyingPartyProperties {
 		public static class Signing {
 
 			/**
-			 * Credentials used for signing and decrypting the SAML authentication
+			 * Credentials used for signing the SAML authentication request.
-			 * request.
 			 */
 			private List<Credential> credentials = new ArrayList<>();
 
@@ -139,7 +144,7 @@ public class Saml2RelyingPartyProperties {
 			public static class Credential {
 
 				/**
-				 * Private key used for signing or decrypting.
+				 * Private key used for signing.
 				 */
 				private Resource privateKeyLocation;
 
@@ -170,6 +175,53 @@ public class Saml2RelyingPartyProperties {
 
 	}
 
+	public static class Decryption {
+
+		/**
+		 * Credentials used for decrypting the SAML authentication request.
+		 */
+		private List<Credential> credentials = new ArrayList<>();
+
+		public List<Credential> getCredentials() {
+			return this.credentials;
+		}
+
+		public void setCredentials(List<Credential> credentials) {
+			this.credentials = credentials;
+		}
+
+		public static class Credential {
+
+			/**
+			 * Private key used for decrypting.
+			 */
+			private Resource privateKeyLocation;
+
+			/**
+			 * Relying Party X509Certificate shared with the identity provider.
+			 */
+			private Resource certificateLocation;
+
+			public Resource getPrivateKeyLocation() {
+				return this.privateKeyLocation;
+			}
+
+			public void setPrivateKeyLocation(Resource privateKey) {
+				this.privateKeyLocation = privateKey;
+			}
+
+			public Resource getCertificateLocation() {
+				return this.certificateLocation;
+			}
+
+			public void setCertificateLocation(Resource certificate) {
+				this.certificateLocation = certificate;
+			}
+
+		}
+
+	}
+
 	/**
 	 * Represents a remote Identity Provider.
 	 */

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/security/saml2/Saml2RelyingPartyRegistrationConfiguration.java

@@ -26,6 +26,7 @@ import java.util.function.Consumer;
 import java.util.stream.Collectors;
 
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
+import org.springframework.boot.autoconfigure.security.saml2.Saml2RelyingPartyProperties.Decryption;
 import org.springframework.boot.autoconfigure.security.saml2.Saml2RelyingPartyProperties.Identityprovider.Verification;
 import org.springframework.boot.autoconfigure.security.saml2.Saml2RelyingPartyProperties.Registration;
 import org.springframework.boot.autoconfigure.security.saml2.Saml2RelyingPartyProperties.Registration.Signing;
@@ -36,6 +37,7 @@ import org.springframework.context.annotation.Configuration;
 import org.springframework.core.io.Resource;
 import org.springframework.security.converter.RsaKeyConverters;
 import org.springframework.security.saml2.core.Saml2X509Credential;
+import org.springframework.security.saml2.core.Saml2X509Credential.Saml2X509CredentialType;
 import org.springframework.security.saml2.provider.service.registration.InMemoryRelyingPartyRegistrationRepository;
 import org.springframework.security.saml2.provider.service.registration.RelyingPartyRegistration;
 import org.springframework.security.saml2.provider.service.registration.RelyingPartyRegistration.AssertingPartyDetails;
@@ -78,6 +80,8 @@ class Saml2RelyingPartyRegistrationConfiguration {
 		builder.assertingPartyDetails(mapIdentityProvider(properties, usingMetadata));
 		builder.signingX509Credentials((credentials) -> properties.getSigning().getCredentials().stream()
 				.map(this::asSigningCredential).forEach(credentials::add));
+		builder.decryptionX509Credentials((credentials) -> properties.getDecryption().getCredentials().stream()
+				.map(this::asDecryptionCredential).forEach(credentials::add));
 		builder.assertingPartyDetails((details) -> details
 				.verificationX509Credentials((credentials) -> properties.getIdentityprovider().getVerification()
 						.getCredentials().stream().map(this::asVerificationCredential).forEach(credentials::add)));
@@ -111,8 +115,13 @@ class Saml2RelyingPartyRegistrationConfiguration {
 	private Saml2X509Credential asSigningCredential(Signing.Credential properties) {
 		RSAPrivateKey privateKey = readPrivateKey(properties.getPrivateKeyLocation());
 		X509Certificate certificate = readCertificate(properties.getCertificateLocation());
-		return new Saml2X509Credential(privateKey, certificate, Saml2X509Credential.Saml2X509CredentialType.SIGNING,
+		return new Saml2X509Credential(privateKey, certificate, Saml2X509CredentialType.SIGNING);
-				Saml2X509Credential.Saml2X509CredentialType.DECRYPTION);
+	}
+
+	private Saml2X509Credential asDecryptionCredential(Decryption.Credential properties) {
+		RSAPrivateKey privateKey = readPrivateKey(properties.getPrivateKeyLocation());
+		X509Certificate certificate = readCertificate(properties.getCertificateLocation());
+		return new Saml2X509Credential(privateKey, certificate, Saml2X509CredentialType.DECRYPTION);
 	}
 
 	private Saml2X509Credential asVerificationCredential(Verification.Credential properties) {

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/security/saml2/Saml2RelyingPartyAutoConfigurationTests.java

@@ -98,7 +98,8 @@ class Saml2RelyingPartyAutoConfigurationTests {
 			assertThat(registration.getAssertingPartyDetails().getSingleSignOnServiceBinding())
 					.isEqualTo(Saml2MessageBinding.POST);
 			assertThat(registration.getAssertingPartyDetails().getWantAuthnRequestsSigned()).isEqualTo(false);
-			assertThat(registration.getSigningX509Credentials()).isNotNull();
+			assertThat(registration.getSigningX509Credentials()).hasSize(1);
+			assertThat(registration.getDecryptionX509Credentials()).hasSize(1);
 			assertThat(registration.getAssertingPartyDetails().getVerificationX509Credentials()).isNotNull();
 			assertThat(registration.getEntityId()).isEqualTo("{baseUrl}/saml2/foo-entity-id");
 		});
@@ -182,6 +183,8 @@ class Saml2RelyingPartyAutoConfigurationTests {
 		return new String[] {
 				PREFIX + ".foo.signing.credentials[0].private-key-location=classpath:saml/private-key-location",
 				PREFIX + ".foo.signing.credentials[0].certificate-location=classpath:saml/certificate-location",
+				PREFIX + ".foo.decryption.credentials[0].private-key-location=classpath:saml/private-key-location",
+				PREFIX + ".foo.decryption.credentials[0].certificate-location=classpath:saml/certificate-location",
 				PREFIX + ".foo.identityprovider.singlesignon.url=https://simplesaml-for-spring-saml.cfapps.io/saml2/idp/SSOService.php",
 				PREFIX + ".foo.identityprovider.singlesignon.binding=post",
 				PREFIX + ".foo.identityprovider.singlesignon.sign-request=false",

spring-boot-project/spring-boot-docs/src/docs/asciidoc/spring-boot-features.adoc

@@ -3866,7 +3866,12 @@ You can register multiple relying parties under the `spring.security.saml2.relyi
 	      relyingparty:
 	        registration:
 	          my-relying-party1:
-	            signing.credentials:
+	            signing:
+                  credentials:
+                  - private-key-location: "path-to-private-key"
+                    certificate-location: "path-to-certificate"
+	            decryption:
+	              credentials:
 	              - private-key-location: "path-to-private-key"
                     certificate-location: "path-to-certificate"
 	            identityprovider:
@@ -3875,12 +3880,15 @@ You can register multiple relying parties under the `spring.security.saml2.relyi
 	                - certificate-location: "path-to-verification-cert"
 	              entity-id: "remote-idp-entity-id1"
 	              sso-url: "https://remoteidp1.sso.url"
-
 	          my-relying-party2:
 	            signing:
 	              credentials:
 	              - private-key-location: "path-to-private-key"
                     certificate-location: "path-to-certificate"
+                decryption:
+	              credentials:
+	              - private-key-location: "path-to-private-key"
+                    certificate-location: "path-to-certificate"
                 identityprovider:
                   verification:
                     credentials: