diff --git a/silkaj/auth.py b/silkaj/auth.py
index d80fc729a839d73f08f4635ab5be8aaea067bbc8..b2161a7df13c9f823f22cd5719ec93efe7a0e249 100644
--- a/silkaj/auth.py
+++ b/silkaj/auth.py
@@ -24,6 +24,11 @@ from duniterpy.key import SigningKey
 from duniterpy.key.scrypt_params import ScryptParams
 
 from silkaj.tools import message_exit
+from silkaj.constants import PUBKEY_PATTERN
+
+SEED_HEX_PATTERN = "^[0-9a-fA-F]{64}$"
+PUBSEC_PUBKEY_PATTERN = "pub: ({0})".format(PUBKEY_PATTERN)
+PUBSEC_SIGNKEY_PATTERN = "sec: ([1-9A-HJ-NP-Za-km-z]{87,90})"
 
 
 @pass_context
@@ -73,14 +78,13 @@ def auth_by_auth_file(ctx):
     if not authfile.is_file():
         message_exit('Error: the file "' + file + '" does not exist')
     filetxt = authfile.open("r").read()
-    # regex for seed (hexadecimal)
-    regex_seed = re.compile("^[0-9a-fA-F]{64}$")
+
     # two regural expressions for the PubSec format
-    regex_pubkey = re.compile("pub: ([1-9A-HJ-NP-Za-km-z]{43,44})", re.MULTILINE)
-    regex_signkey = re.compile("sec: ([1-9A-HJ-NP-Za-km-z]{87,90})", re.MULTILINE)
+    regex_pubkey = re.compile(PUBSEC_PUBKEY_PATTERN, re.MULTILINE)
+    regex_signkey = re.compile(PUBSEC_SIGNKEY_PATTERN, re.MULTILINE)
 
-    # Seed format
-    if re.search(regex_seed, filetxt):
+    # Seed hexadecimal format
+    if re.search(re.compile(SEED_HEX_PATTERN), filetxt):
         return SigningKey.from_seedhex_file(file)
     # PubSec format
     elif re.search(regex_pubkey, filetxt) and re.search(regex_signkey, filetxt):
diff --git a/silkaj/constants.py b/silkaj/constants.py
index 17185490b1d3c45d9b203bf6ad541dfbffc8fec9..1d4c3574226e6b2e8e3c0d71562f473f9ea0b271 100644
--- a/silkaj/constants.py
+++ b/silkaj/constants.py
@@ -26,3 +26,4 @@ SOURCES_PER_TX = 40
 SUCCESS_EXIT_STATUS = 0
 FAILURE_EXIT_STATUS = 1
 BMA_MAX_BLOCKS_CHUNK_SIZE = 5000
+PUBKEY_PATTERN = "[1-9A-HJ-NP-Za-km-z]{43,44}"
diff --git a/silkaj/crypto_tools.py b/silkaj/crypto_tools.py
index af8726f5e413f7f98303f96c773378f85928da78..ae28606ed56dce45d404b94cab428a4d4423ab57 100644
--- a/silkaj/crypto_tools.py
+++ b/silkaj/crypto_tools.py
@@ -18,6 +18,12 @@ along with Silkaj. If not, see <https://www.gnu.org/licenses/>.
 import re
 from nacl import encoding, hash
 
+from silkaj.constants import PUBKEY_PATTERN
+
+PUBKEY_DELIMITED_PATTERN = "^{0}$".format(PUBKEY_PATTERN)
+CHECKSUM_PATTERN = "[1-9A-HJ-NP-Za-km-z]{3}"
+PUBKEY_CHECKSUM_PATTERN = "^{0}!{1}$".format(PUBKEY_PATTERN, CHECKSUM_PATTERN)
+
 
 def check_public_key(pubkey, display_error):
     """
@@ -25,13 +31,9 @@ def check_public_key(pubkey, display_error):
     Check pubkey checksum which could be append after the pubkey
     If check pass: return pubkey
     """
-    regex = re.compile("^[1-9A-HJ-NP-Za-km-z]{43,44}$")
-    regex_checksum = re.compile(
-        "^[1-9A-HJ-NP-Za-km-z]{43,44}" + "![1-9A-HJ-NP-Za-km-z]{3}$"
-    )
-    if re.search(regex, pubkey):
+    if re.search(re.compile(PUBKEY_DELIMITED_PATTERN), pubkey):
         return pubkey
-    elif re.search(regex_checksum, pubkey):
+    elif re.search(re.compile(PUBKEY_CHECKSUM_PATTERN), pubkey):
         pubkey, checksum = pubkey.split("!")
         pubkey_byte = b58_decode(pubkey)
         checksum_calculed = b58_encode(