2 files changed, 5 insertions, 2 deletions
diff --git a/src/lib/kdf/hkdf/hkdf.cpp b/src/lib/kdf/hkdf/hkdf.cpp
index 6f83853f9..56dc72f09 100644
--- a/src/lib/kdf/hkdf/hkdf.cpp
+++ b/src/lib/kdf/hkdf/hkdf.cpp
@@ -22,7 +22,8 @@ HKDF* HKDF::make(const Spec& spec)
 
 size_t HKDF::kdf(byte out[], size_t out_len,
                  const byte secret[], size_t secret_len,
-                 const byte salt[], size_t salt_len) const
+                 const byte salt[], size_t salt_len,
+                 const byte label[], size_t label_len) const
    {
    m_prf->set_key(secret, secret_len);
 
@@ -33,6 +34,7 @@ size_t HKDF::kdf(byte out[], size_t out_len,
    while(offset != out_len && counter != 0)
       {
       m_prf->update(h);
+      m_prf->update(label, label_len);
       m_prf->update(salt, salt_len);
       m_prf->update(counter++);
       m_prf->final(h);
diff --git a/src/lib/kdf/hkdf/hkdf.h b/src/lib/kdf/hkdf/hkdf.h
index 3e3e2b73a..1dba82ee2 100644
--- a/src/lib/kdf/hkdf/hkdf.h
+++ b/src/lib/kdf/hkdf/hkdf.h
@@ -31,7 +31,8 @@ class BOTAN_DLL HKDF final : public KDF
 
       size_t kdf(byte out[], size_t out_len,
                  const byte secret[], size_t secret_len,
-                 const byte salt[], size_t salt_len) const override;
+                 const byte salt[], size_t salt_len,
+                 const byte label[], size_t label_len) const override;
 
    private:
       std::unique_ptr<MessageAuthenticationCode> m_prf;