diff --git a/fusee/fusee-secondary/src/key_derivation.c b/fusee/fusee-secondary/src/key_derivation.c
index 30357aeab..cb423b78e 100644
--- a/fusee/fusee-secondary/src/key_derivation.c
+++ b/fusee/fusee-secondary/src/key_derivation.c
@@ -33,6 +33,8 @@ static const uint8_t masterkey_4x_seed[0x10] = {
     0x2D, 0xC1, 0xF4, 0x8D, 0xF3, 0x5B, 0x69, 0x33, 0x42, 0x10, 0xAC, 0x65, 0xDA, 0x90, 0x46, 0x66
 };
 
+static nx_dec_keyblob_t __attribute__((aligned(16))) g_dec_keyblobs[32];
+
 static int get_tsec_key(void *dst, const void *tsec_fw, size_t tsec_fw_size, uint32_t tsec_key_id) {
     return tsec_query((u32)tsec_fw, dst, tsec_key_id);
 }
@@ -61,10 +63,43 @@ static bool safe_memcmp(uint8_t *a, uint8_t *b, size_t sz) {
     return different != 0;
 }
 
+static int decrypt_keyblob(const nx_keyblob_t *keyblobs, uint32_t revision, uint32_t available_revision) {
+    nx_keyblob_t keyblob;
+    nx_dec_keyblob_t *dec = &g_dec_keyblobs[revision];
+    uint8_t work_buffer[0x10];
+    
+    if (get_keyblob(&keyblob, revision, keyblobs, available_revision) != 0) {
+        return -1;
+    }
+    
+    se_aes_ecb_decrypt_block(0xD, work_buffer, 0x10, keyblob_seeds[revision], 0x10);
+    decrypt_data_into_keyslot(KEYSLOT_SWITCH_TEMPKEY, 0xE, work_buffer, 0x10);
+    decrypt_data_into_keyslot(0xB, KEYSLOT_SWITCH_TEMPKEY, keyblob_mac_seed, 0x10);
+    
+    /* Validate keyblob. */
+    se_compute_aes_128_cmac(0xB, work_buffer, 0x10, keyblob.mac + sizeof(keyblob.mac), sizeof(keyblob) - sizeof(keyblob.mac));
+    if (safe_memcmp(keyblob.mac, work_buffer, 0x10)) {
+        return -1;
+    }
+    
+    /* Decrypt keyblob. */
+    se_aes_ctr_crypt(0xD, dec, sizeof(dec), keyblob.data, sizeof(keyblob.data), keyblob.ctr, sizeof(keyblob.ctr));
+    return 0;
+}
+
+int load_package1_key(uint32_t revision) {
+    if (revision > MASTERKEY_REVISION_500_CURRENT) {
+        return -1;
+    }
+    
+    set_aes_keyslot(0xB, g_dec_keyblobs[revision].keys[8], 0x10);
+    return 0;
+}
+
 /* Derive all Switch keys. */
 int derive_nx_keydata(uint32_t target_firmware, const nx_keyblob_t *keyblobs, uint32_t available_revision, const void *tsec_fw, size_t tsec_fw_size) {
     uint8_t work_buffer[0x10];
-    nx_keyblob_t keyblob;
+    nx_dec_keyblob_t dec_keyblob;
 
     /* TODO: Set keyslot flags properly in preparation of derivation. */
     set_aes_keyslot_flags(0xE, 0x15);
@@ -75,13 +110,16 @@ int derive_nx_keydata(uint32_t target_firmware, const nx_keyblob_t *keyblobs, ui
         return -1;
     }
     set_aes_keyslot(0xD, work_buffer, 0x10);
-
-    /* Get keyblob, always try to set up the highest possible master key. */
-    /* TODO: Should we iterate, trying lower keys on failure? */
-    if (get_keyblob(&keyblob, MASTERKEY_REVISION_500_CURRENT, keyblobs, available_revision) != 0) {
-        return -1;
+    
+    /* Decrypt all keyblobs. */
+    for (unsigned int rev = MASTERKEY_REVISION_100_230; rev < MASTERKEY_REVISION_500_CURRENT; rev++) {
+        int ret = decrypt_keyblob(keyblobs, rev, available_revision);
+        if (ret) {
+            return ret;
+        }
     }
 
+    /* Always try to set up the highest possible master key. */
     /* Derive both keyblob key 1, and keyblob key latest. */
     se_aes_ecb_decrypt_block(0xD, work_buffer, 0x10, keyblob_seeds[MASTERKEY_REVISION_100_230], 0x10);
     decrypt_data_into_keyslot(0xF, 0xE, work_buffer, 0x10);
@@ -90,24 +128,12 @@ int derive_nx_keydata(uint32_t target_firmware, const nx_keyblob_t *keyblobs, ui
 
     /* Clear the SBK. */
     clear_aes_keyslot(0xE);
-    se_aes_ecb_decrypt_block(0xD, work_buffer, 0x10, keyblob_mac_seed, 0x10);
-    decrypt_data_into_keyslot(0xB, 0xD, keyblob_mac_seed, 0x10);
-
-    /* Validate keyblob. */
-    se_compute_aes_128_cmac(0xB, work_buffer, 0x10, keyblob.mac + sizeof(keyblob.mac), sizeof(keyblob) - sizeof(keyblob.mac));
-    if (safe_memcmp(keyblob.mac, work_buffer, 0x10)) {
-        return -1;
-    }
-
-    /* Decrypt keyblob. */
-    se_aes_ctr_crypt(0xD, keyblob.data, sizeof(keyblob.data), keyblob.data, sizeof(keyblob.data), keyblob.ctr, sizeof(keyblob.ctr));
+    
+    /* Get latest keyblob. */
+    dec_keyblob = g_dec_keyblobs[MASTERKEY_REVISION_500_CURRENT];
 
     /* Get needed data. */
-    set_aes_keyslot(0xC, keyblob.keys[0], 0x10);
-    set_aes_keyslot(0xB, keyblob.keys[8], 0x10);
-
-    /* Clear keyblob. */
-    memset(keyblob.data, 0, sizeof(keyblob.data));
+    set_aes_keyslot(0xC, dec_keyblob.keys[0], 0x10);
 
     /* Derive keys for Exosphere, lock critical keyslots. */
     switch (target_firmware) {
diff --git a/fusee/fusee-secondary/src/key_derivation.h b/fusee/fusee-secondary/src/key_derivation.h
index 1ef185417..86b35a82a 100644
--- a/fusee/fusee-secondary/src/key_derivation.h
+++ b/fusee/fusee-secondary/src/key_derivation.h
@@ -22,17 +22,22 @@ typedef enum BisPartition {
     BisPartition_UserSystem = 2,
 } BisPartition;
 
+typedef struct {
+    uint8_t keys[9][0x10];
+} nx_dec_keyblob_t;
+
 typedef struct nx_keyblob_t {
     uint8_t mac[0x10];
     uint8_t ctr[0x10];
     union {
         uint8_t data[0x90];
-        uint8_t keys[9][0x10];
+        nx_dec_keyblob_t dec_blob;
     };
 } nx_keyblob_t;
 
 /* TSEC fw must be 0x100-byte-aligned. */
 int derive_nx_keydata(uint32_t target_firmware, const nx_keyblob_t *keyblobs, uint32_t available_revision, const void *tsec_fw, size_t tsec_fw_size);
+int load_package1_key(uint32_t revision);
 void finalize_nx_keydata(uint32_t target_firmware);
 
 void derive_bis_key(void *dst, BisPartition partition_id, uint32_t target_firmware);