Espionage was a weird job, and I was beginning to suspect it was bad for my eyes. If I ended up needing glasses after this, I was going to blame Sensei for it. Sure, I was already wearing glasses as part of my disguise, but they were fake, and I'm not in the mood to make them part of my permanent appearance. Why couldn't we codebreak under proper lighting? Haah... whatever. The inn room had to remain dark so as not to draw suspicion from outside, except for a covered lamp on the floor where we were kneeling, deciphering the rows of symbols. Jiraiya-sensei had placed seals on the door, window, walls, and even the floor to ensure no sound escaped and that nobody could observe us through any other means without alerting us first. After Minato and I had written out everything we remembered and compared our versions, they turned out to be identical, so... work had begun.
"I hate codes," I said quietly, probably for the tenth time in a row.
"We heard you already." Minato glanced at me with a faint smile, elbowing me.
"Sssh!" Jiraiya-sensei did not look up when hissing at us, of course, "Both of you, quiet. If you have time to speak, you have time to work."
He had been staring at the page for several hours without making a single joke, which was a sure sign that he was taking this very, very seriously. I couldn't blame him, but I was already feeling tired, and not in the pleasant way that came after training. My eyes felt dry, my head hurt, but I had not gotten any closer to understanding any of the codes. Giving up for a little bit, I leaned backward, rubbing my face.
"I think I'm starting to understand it." Sensei just said it the moment I was about to rest my eyes, forcing me to lean back again, "This is not a full military cipher, because it has the signs of a layered field code. At least, that's how it starts."
"What does that mean?" I asked, stifling a yawn.
"It means it was made for speed rather than absolute secrecy. It makes sense." He looked at us while speaking. "This is still their territory, and they feel safe. Their couriers need to be able to read orders quickly, without carrying a heavy codebook and spending days deciphering their own instructions." Then, he pointed to the first cluster of symbols. "This part I recognize from the previous war. Kirigakure used a similar substitution table for naval carriers, and in that, each symbol stood for a sound or a common operational word."
"They didn't change it?" Minato asked, grimacing.
"They did, as it is not identical, but the base of it is the same. They just changed the alphabet and added false symbols, but some habits remained. I can spot them, and I was breaking the basic symbols it has until now." Doing so, Jiraiya moved the brush toward the center of the message. "However, there is a switch here." He pointed at it, furrowing his brows, then moved the brush near the end. "And a switchback here."
"Double layering?" I asked, making them both look at me. "I mean, they encoded the message once, then changed how the code worked halfway through?"
"Probably," Jiraiya muttered, pulling the page closer to his face. "The beginning uses a modified form of the old courier cipher, and then the sender changes the substitution table in the middle before returning to the original table for the final line."
"Why switch back?"
"Authentication," Minato answered before Jiraiya could, as he picked up the page next, studying it. "If the final line returns to the opening cipher, the recipient can confirm that the person who encoded it knew both the first key and the switching instruction. Someone who only broke part of the message might decode the center incorrectly."
"Of course. Very obvious." I said, but none of them were buying it, and I didn't try to sound convincing at all. Instead, I just spoke what first came to mind from code-breaking documentaries I watched somewhere in the past, "What if the numbers are meant for substitution?" I offered. "They could tell the reader how much to shift the cipher, hm?"
"That..." Jiraiya's eyes moved toward them, starting to consider it.
"And the repeated symbols are probably common operational words." I continued, "They appear multiple times, so they have to mean something important, whatever instructions Kiri uses all the time."
"Not bad, Renjiro," To my surprise, Jiraiya began listing each repeated symbol, then marked how often it appeared and where it appeared. "Duplicated groups can be entire codewords," he added. "Military field ciphers often give common words their own symbol, and the switch in the middle probably used it to conceal the core of the orders. As for the opening, it is likely a status statement."
"We already know they're maintaining the unnatural fog," I said. "Could that be our starting point?"
"A likely scenario," Jiraiya muttered, and using his previous knowledge of their way of coding their messages, he wrote several likely phrases beneath the opening line.
FOG ESTABLISHED.
FOG MAINTAINED.
SCREEN MAINTAINED.
SEA LANES COVERED.
He compared their lengths, repetitions, and placement with the encoded symbols, and most failed quickly, as they didn't fit at all. Then Minato reached forward, trying his own.
"What about 'Fog screen maintained over lanes'?" He pointed to the first and fourth symbol clusters. "These two repeat later near directional markers. If this one means 'screen,' then the later lines could refer to western, central, and eastern screens."
Following Minato's idea, Jiraiya worked through it as the two began cracking substitutions and spoke like two old men working on a difficult crossword puzzle. As for me, I just watched and sometimes offered incredibly valuable moral support. I was glad to stay out of it and let them break their heads open over the code. Eventually, Jiraiya wrote the completed translation beneath the first line.
"FOG SCREEN MAINTAINED OVER LANES."
"So," I muttered, reading it, "we spent hours proving something we already knew."
"We cracked their method of coding the start and the end of the letter," Minato argued.
Not wanting to stop, Jiraiya continued quickly, matched the first decoded symbols to the table, and then applied them to the second line. It worked for the first few characters before dissolving into nonsense again. Yeah... There was the switch. Using the numbers, and my suggestion, he shifted the cipher table by the stated amount, moving every symbol several spaces through the keyed alphabet, and suddenly, the next cluster began producing recognizable fragments.
"WEST. SCREEN. OPEN."
"The first number tells the reader how far to shift the symbol table." Jiraiya muttered as he was kept going, "The full pair can also be read as a square on a naval grid."
"So they are the key and the coordinates?" I snorted, "Can't believe they indeed did that... If someone cracks one use, they find the other. Sloppy work!"
"It is designed for disposable messages." He explained, "By the time an enemy breaks it, the orders should already have been carried out. We are the prime example for it working..."
For the next few hours, they kept doing the same method, over and over, as the cipher shifted twice more. By then, I did not need the full message to see the picture because it was as clear as day that Kiri was closing routes around the Uzumaki islands, making sure civilian and allied ships could not pass unnoticed. The coordinates they mentioned were chosen to avoid Konoha's usual patrol routes while remaining hidden in the spreading fog. Eventually, the second section became readable as the two of them finished cracking it.
"WESTERN SCREEN ESTABLISHED. MAIN LANE CLOSED. EASTERN SCREEN ESTABLISHED. SECOND FOG LAYER AT NIGHT. MAIN LANE OPENS IN FIVE DAYS."
"This means," Minato muttered, rereading it, "That the western and eastern groups are already in place."
"And the main lane is closed to ordinary traffic," Jiraiya nodded. "That explains the missing ships and diverted traders."
"Why reopen it in five days?" I asked.
"To let their own main force through," Jiraiya answered after a brief silence. "The remaining issue is..." He muttered, "That's the last part, probably has a third cipher because it doesn't make sense."
"STONE STORES READY."
"Is there a quarry here or something?" Jiraiya asked, studying the sea chart. "An island they can frog hop from into Uzumaki territory?"
"There are several on these islands," Minato said, also looking at the map. "But they are too far... It could mean supplies, too."
"No." I shook my head, realizing the answer, "I don't think it's literal."
"..." Both looked at me, making me sigh.
"If this were about stone supplies, why include it in a message about a naval encirclement?"
"Ballast," Minato suggested, though he didn't sound convinced, "Maybe they made something to travel underwater."
"Good idea," I said, nodding, amazed by how his brain worked. "But I don't think it's a submarine."
"A what?" He asked, but then Jirayia added his own idea.
"Construction materials. A pontoon bridge over the turbulent waters..." but as he was speaking, looking at me, he had to realize what I was meaning. "Iwagakure," he said at last, his mouth remaining open for a moment.
"Yeah." I nodded, "I think so. And..." I pointed to another weird line.
"SKY SPEAR READY."
"Iwagakure and Kumogakure," Minato said instead of Jiraiya this time, "Damn it... Three nations are preparing for war against the Uzumakis?! They won't stand a chance!"
"And if so," I kept speaking, "I don't think these are coordinates," I was pointing at the numbers towards the middle, as Jiraiya began comparing them to the sea grid.
"They aren't." He concluded the same thing, "The sequence, if it were one, falls outside the chart."
"Then they are unit designations," Minato nodded. "Seven could mean the Seven Swordsmen."
"If this is as big as it seems," I shrugged, "The Swordsmen would be assigned to this operation, for sure. No wonder we saw them here. With how Kiri is moving an army through the fog, they've already surrounded the main sea lanes. They harass the boats to make us and the Uzumakis look at certain spots, while slipping the bulk of the army past where we aren't looking. By this message, Iwa is moving too, and Kumo is ready to strike. Sensei, I don't think we have much time before the three bring down the hammer on the Uzumakis."
"The main lane opens in five days." Minato whispered, "We have barely four days then, counting today..."
"The mission is over," Sensei said at once as our heads snapped up to look at him.
"We return to Konoha?" Minato asked.
"No." He answered at once, "If we travel back to Konoha first, it will be too late."
"Then we send a toad," I said, and he was already doing that, summoning one.
"Yes, I will send one with the message to Hiruzen-sensei," he nodded, writing as fast as he could, "But we go directly to Uzushiogakure."
"So what do we use?" I asked, standing up and ready to bounce.
"We are going to steal a boat," Jiraiya sealed the translated message into a scroll, along with his report, giving it to the toad before sending it away. "We are going to the harbor, take the fastest vessel, and head for Uzushiogakure."
"Finally, an espionage method I understand." I grinned, as this was much more up my alley than sneaking around. Well... we still need to sneak around, but it was better than code-breaking.
"We have to be fast," He said, and I have never seen him so grave, "Also..." He put a hand on both of our shoulders, "After we reach the Uzumaki's, we won't have time to leave, and we will be in the middle of an enemy invasion. Are you ready for it?"
"Sensei," I spoke up first, tilting my head, "Do you remember what I said when we first visited them? My warning?"
"And they took it seriously." He nodded, slowly smiling, making me grin.
"Well then!" I nodded, feeling a bit more lighthearted. "I think there is a high chance that we can repel whatever they throw at us!"
"Don't jinx us, Renji." Minato snorted, but was smiling just the same, "But he is right, Sensei. It's Kushina's home, her clan, and our allies. We can't, and we won't abandon them."