diff --git a/internal/service/api/handlers/register.go b/internal/service/api/handlers/register.go
index 3b0ea5e..5d083b2 100644
--- a/internal/service/api/handlers/register.go
+++ b/internal/service/api/handlers/register.go
@@ -246,12 +246,12 @@ func Register(w http.ResponseWriter, r *http.Request) {
 }
 
 func verifySod(
-		signedAttributes []byte,
-		encapsulatedContent []byte,
-		signature []byte,
-		cert *x509.Certificate,
-		algorithmPair types.AlgorithmPair,
-		cfg *config.VerifierConfig,
+	signedAttributes []byte,
+	encapsulatedContent []byte,
+	signature []byte,
+	cert *x509.Certificate,
+	algorithmPair types.AlgorithmPair,
+	cfg *config.VerifierConfig,
 ) error {
 	if err := validateSignedAttributes(signedAttributes, encapsulatedContent, algorithmPair.HashAlgorithm); err != nil {
 		return &types.SodError{
@@ -300,9 +300,9 @@ func parseCertificate(pemFile []byte) (*x509.Certificate, error) {
 }
 
 func validateSignedAttributes(
-		signedAttributes,
-		encapsulatedContent []byte,
-		hashAlgorithm types.HashAlgorithm,
+	signedAttributes,
+	encapsulatedContent []byte,
+	hashAlgorithm types.HashAlgorithm,
 ) error {
 	signedAttributesASN1 := make([]asn1.RawValue, 0)
 
@@ -340,10 +340,10 @@ func validateSignedAttributes(
 }
 
 func verifySignature(
-		signature []byte,
-		cert *x509.Certificate,
-		signedAttributes []byte,
-		algorithmPair types.AlgorithmPair,
+	signature []byte,
+	cert *x509.Certificate,
+	signedAttributes []byte,
+	algorithmPair types.AlgorithmPair,
 ) error {
 	h := types.GeneralHash(algorithmPair.HashAlgorithm)
 	h.Write(signedAttributes)
diff --git a/internal/service/api/requests/register.go b/internal/service/api/requests/register.go
index 9d1ba51..4b39b3b 100644
--- a/internal/service/api/requests/register.go
+++ b/internal/service/api/requests/register.go
@@ -63,6 +63,10 @@ func validateRegister(r resources.RegisterResponse) error {
 			validation.Required,
 			validation.Length(1, 4096),
 		),
+		"/data/attributes/document_sod/aa_signature": validation.Validate(
+			r.Data.Attributes.DocumentSod.AaSignature,
+			validation.Length(0, 4096),
+		),
 		"/data/attributes/document_sod/pem_file": validation.Validate(
 			r.Data.Attributes.DocumentSod.PemFile,
 			validation.Required,